Randomized Experiments, Blocking, and Blinding

AP Statistics Practice

Randomized Experiments, Blocking, and Blinding

Randomized Experiments, Blocking, and Blinding practice bank: Solve the visible multiple-choice and free-response questions, then compare every step with the worked answers.

MCQs36

FRQ sets14

AnswersVisible

Topic links73 pages

Randomized Experiments, Blocking, and Blinding: formulas and targets

Block	Group similar units before random assignment.
Blinding	Keep treatment identity hidden when practical.

Randomized Experiments, Blocking, and Blinding multiple-choice practice

Question 1. Randomized Experiments, Blocking, and Blinding

A wildlife clinic in Pacific Northwest during a two-month observation window will compare two programs affecting recovery time. Describe a randomized design that uses age group as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Assign the better-performing block to one treatment and the other block to the second treatment.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: B

At the wildlife clinic in Pacific Northwest during a two-month observation window, group the animals by age group, then randomly assign units within each block to the two programs affecting recovery time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 2. Randomized Experiments, Blocking, and Blinding

A municipal water office in Cedar Grove during a service-improvement study will compare two programs affecting monthly household use. Describe a randomized design that uses site as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Measure only one treatment because blocking removes the need for a control group.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: B

At the municipal water office in Cedar Grove during a service-improvement study, group the accounts by site, then randomly assign units within each block to the two programs affecting monthly household use. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 3. Randomized Experiments, Blocking, and Blinding

A solar installer in Westview during a school-year data collection will compare two programs affecting daily energy output. Describe a randomized design that uses previous experience as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Measure only one treatment because blocking removes the need for a control group.
C. Randomly sample a population but let participants choose treatments.
D. Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the solar installer in Westview during a school-year data collection, group the installations by previous experience, then randomly assign units within each block to the two programs affecting daily energy output. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 4. Randomized Experiments, Blocking, and Blinding

A municipal emergency dispatch center in Desert County during a winter readiness review will compare two programs affecting response time. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Measure only one treatment because blocking removes the need for a control group.
B. Randomly sample a population but let participants choose treatments.
C. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: C

At the municipal emergency dispatch center in Desert County during a winter readiness review, group the calls by baseline score, then randomly assign units within each block to the two programs affecting response time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 5. Randomized Experiments, Blocking, and Blinding

A university advising center in Capital Region during a multiweek validation study will compare two programs affecting appointment wait time. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Measure only one treatment because blocking removes the need for a control group.
C. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Randomly sample a population but let participants choose treatments.

Answer: C

At the university advising center in Capital Region during a multiweek validation study, group the appointments by baseline score, then randomly assign units within each block to the two programs affecting appointment wait time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 6. Randomized Experiments, Blocking, and Blinding

A school district in Atlantic Corridor during a monthly quality review will compare two programs affecting lunch-program participation. Describe a randomized design that uses age group as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Measure only one treatment because blocking removes the need for a control group.
D. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the school district in Atlantic Corridor during a monthly quality review, group the students by age group, then randomly assign units within each block to the two programs affecting lunch-program participation. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 7. Randomized Experiments, Blocking, and Blinding

A farm cooperative in Mountain Region during a quarterly performance study will compare two programs affecting crop yield. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Measure only one treatment because blocking removes the need for a control group.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: B

At the farm cooperative in Mountain Region during a quarterly performance study, group the plots by baseline score, then randomly assign units within each block to the two programs affecting crop yield. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 8. Randomized Experiments, Blocking, and Blinding

A public health department in Capital Region during a fall 2026 audit will compare two programs affecting vaccination appointment completion. Describe a randomized design that uses previous experience as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Measure only one treatment because blocking removes the need for a control group.
D. Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the public health department in Capital Region during a fall 2026 audit, group the residents by previous experience, then randomly assign units within each block to the two programs affecting vaccination appointment completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 9. Randomized Experiments, Blocking, and Blinding

A municipal emergency dispatch center in Metro East during a fall 2026 audit will compare two programs affecting response time. Describe a randomized design that uses age group as a block and explain the benefit.

A. Measure only one treatment because blocking removes the need for a control group.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Randomly sample a population but let participants choose treatments.
D. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the municipal emergency dispatch center in Metro East during a fall 2026 audit, group the calls by age group, then randomly assign units within each block to the two programs affecting response time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 10. Randomized Experiments, Blocking, and Blinding

A regional airport authority in Coastal Plains during a community outreach cycle will compare two programs affecting security wait time. Describe a randomized design that uses previous experience as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Measure only one treatment because blocking removes the need for a control group.
C. Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Randomly sample a population but let participants choose treatments.

Answer: C

At the regional airport authority in Coastal Plains during a community outreach cycle, group the travelers by previous experience, then randomly assign units within each block to the two programs affecting security wait time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 11. Randomized Experiments, Blocking, and Blinding

A digital learning platform in Mountain Region during a weekday operations study will compare two programs affecting lesson completion. Describe a randomized design that uses age group as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Measure only one treatment because blocking removes the need for a control group.
C. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Randomly sample a population but let participants choose treatments.

Answer: C

At the digital learning platform in Mountain Region during a weekday operations study, group the learners by age group, then randomly assign units within each block to the two programs affecting lesson completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 12. Randomized Experiments, Blocking, and Blinding

A community bank in Riverbend during a semester-long cohort study will compare two programs affecting mobile-deposit adoption. Describe a randomized design that uses site as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Measure only one treatment because blocking removes the need for a control group.
D. Randomly sample a population but let participants choose treatments.

Answer: B

At the community bank in Riverbend during a semester-long cohort study, group the customers by site, then randomly assign units within each block to the two programs affecting mobile-deposit adoption. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 13. Randomized Experiments, Blocking, and Blinding

A digital learning platform in Cedar Grove during a follow-up evaluation period will compare two programs affecting lesson completion. Describe a randomized design that uses site as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Measure only one treatment because blocking removes the need for a control group.
C. Assign the better-performing block to one treatment and the other block to the second treatment.
D. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the digital learning platform in Cedar Grove during a follow-up evaluation period, group the learners by site, then randomly assign units within each block to the two programs affecting lesson completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 14. Randomized Experiments, Blocking, and Blinding

A city recreation department in Metro East during a baseline measurement week will compare two programs affecting program satisfaction. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Randomly sample a population but let participants choose treatments.
C. Measure only one treatment because blocking removes the need for a control group.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: A

At the city recreation department in Metro East during a baseline measurement week, group the participants by baseline score, then randomly assign units within each block to the two programs affecting program satisfaction. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 15. Randomized Experiments, Blocking, and Blinding

A public high school in Great Lakes during a pre-exam training cycle will compare two programs affecting algebra benchmark completion. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Measure only one treatment because blocking removes the need for a control group.
D. Randomly sample a population but let participants choose treatments.

Answer: A

At the public high school in Great Lakes during a pre-exam training cycle, group the students by baseline score, then randomly assign units within each block to the two programs affecting algebra benchmark completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 16. Randomized Experiments, Blocking, and Blinding

A school district in North Valley during a yearly program evaluation will compare two programs affecting lunch-program participation. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Measure only one treatment because blocking removes the need for a control group.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Randomly sample a population but let participants choose treatments.

Answer: C

At the school district in North Valley during a yearly program evaluation, group the students by baseline score, then randomly assign units within each block to the two programs affecting lunch-program participation. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 17. Randomized Experiments, Blocking, and Blinding

A regional manufacturer in Sunbelt district during a spring 2027 pilot will compare two programs affecting part diameter. Describe a randomized design that uses age group as a block and explain the benefit.

A. Measure only one treatment because blocking removes the need for a control group.
B. Randomly sample a population but let participants choose treatments.
C. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: C

At the regional manufacturer in Sunbelt district during a spring 2027 pilot, group the parts by age group, then randomly assign units within each block to the two programs affecting part diameter. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 18. Randomized Experiments, Blocking, and Blinding

A solar installer in Westview during a spring 2027 pilot will compare two programs affecting daily energy output. Describe a randomized design that uses age group as a block and explain the benefit.

A. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Randomly sample a population but let participants choose treatments.
C. Assign the better-performing block to one treatment and the other block to the second treatment.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: A

At the solar installer in Westview during a spring 2027 pilot, group the installations by age group, then randomly assign units within each block to the two programs affecting daily energy output. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 19. Randomized Experiments, Blocking, and Blinding

A municipal water office in South Harbor during a winter readiness review will compare two programs affecting monthly household use. Describe a randomized design that uses previous experience as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Randomly sample a population but let participants choose treatments.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: B

At the municipal water office in South Harbor during a winter readiness review, group the accounts by previous experience, then randomly assign units within each block to the two programs affecting monthly household use. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 20. Randomized Experiments, Blocking, and Blinding

A municipal water office in Prairie District during a follow-up evaluation period will compare two programs affecting monthly household use. Describe a randomized design that uses age group as a block and explain the benefit.

A. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Randomly sample a population but let participants choose treatments.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: A

At the municipal water office in Prairie District during a follow-up evaluation period, group the accounts by age group, then randomly assign units within each block to the two programs affecting monthly household use. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 21. Randomized Experiments, Blocking, and Blinding

A recycling program in Atlantic Corridor during a regional benchmarking study will compare two programs affecting weekly material weight. Describe a randomized design that uses site as a block and explain the benefit.

A. Measure only one treatment because blocking removes the need for a control group.
B. Randomly sample a population but let participants choose treatments.
C. Assign the better-performing block to one treatment and the other block to the second treatment.
D. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the recycling program in Atlantic Corridor during a regional benchmarking study, group the households by site, then randomly assign units within each block to the two programs affecting weekly material weight. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 22. Randomized Experiments, Blocking, and Blinding

A county library in Riverbend during a fall 2026 audit will compare two programs affecting weekly program attendance. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Randomly sample a population but let participants choose treatments.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: B

At the county library in Riverbend during a fall 2026 audit, group the visitors by baseline score, then randomly assign units within each block to the two programs affecting weekly program attendance. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 23. Randomized Experiments, Blocking, and Blinding

A county election office in Coastal Plains during a randomized pilot period will compare two programs affecting ballot-processing time. Describe a randomized design that uses site as a block and explain the benefit.

A. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Randomly sample a population but let participants choose treatments.
C. Measure only one treatment because blocking removes the need for a control group.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: A

At the county election office in Coastal Plains during a randomized pilot period, group the ballots by site, then randomly assign units within each block to the two programs affecting ballot-processing time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 24. Randomized Experiments, Blocking, and Blinding

A food safety laboratory in Riverbend during a winter readiness review will compare two programs affecting sample concentration. Describe a randomized design that uses age group as a block and explain the benefit.

A. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Randomly sample a population but let participants choose treatments.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: A

At the food safety laboratory in Riverbend during a winter readiness review, group the samples by age group, then randomly assign units within each block to the two programs affecting sample concentration. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 25. Randomized Experiments, Blocking, and Blinding

A county library in Mountain Region during a weekday operations study will compare two programs affecting weekly program attendance. Describe a randomized design that uses previous experience as a block and explain the benefit.

A. Measure only one treatment because blocking removes the need for a control group.
B. Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Randomly sample a population but let participants choose treatments.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: B

At the county library in Mountain Region during a weekday operations study, group the visitors by previous experience, then randomly assign units within each block to the two programs affecting weekly program attendance. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 26. Randomized Experiments, Blocking, and Blinding

A solar installer in New England network during a service-improvement study will compare two programs affecting daily energy output. Describe a randomized design that uses age group as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Randomly sample a population but let participants choose treatments.
C. Measure only one treatment because blocking removes the need for a control group.
D. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the solar installer in New England network during a service-improvement study, group the installations by age group, then randomly assign units within each block to the two programs affecting daily energy output. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 27. Randomized Experiments, Blocking, and Blinding

A city recreation department in Mountain Region during a monthly quality review will compare two programs affecting program satisfaction. Describe a randomized design that uses previous experience as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Measure only one treatment because blocking removes the need for a control group.
D. Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the city recreation department in Mountain Region during a monthly quality review, group the participants by previous experience, then randomly assign units within each block to the two programs affecting program satisfaction. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by previous experience, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 28. Randomized Experiments, Blocking, and Blinding

A grocery cooperative in Metro East during a quarterly performance study will compare two programs affecting checkout time. Describe a randomized design that uses site as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Measure only one treatment because blocking removes the need for a control group.
C. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: C

At the grocery cooperative in Metro East during a quarterly performance study, group the customers by site, then randomly assign units within each block to the two programs affecting checkout time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 29. Randomized Experiments, Blocking, and Blinding

A public health department in Cedar Grove during a randomized pilot period will compare two programs affecting vaccination appointment completion. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Measure only one treatment because blocking removes the need for a control group.
C. Randomly sample a population but let participants choose treatments.
D. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the public health department in Cedar Grove during a randomized pilot period, group the residents by baseline score, then randomly assign units within each block to the two programs affecting vaccination appointment completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 30. Randomized Experiments, Blocking, and Blinding

A regional airport authority in Prairie District during a fall 2026 audit will compare two programs affecting security wait time. Describe a randomized design that uses site as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Measure only one treatment because blocking removes the need for a control group.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: B

At the regional airport authority in Prairie District during a fall 2026 audit, group the travelers by site, then randomly assign units within each block to the two programs affecting security wait time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by site, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 31. Randomized Experiments, Blocking, and Blinding

A regional manufacturer in New England network during a yearly program evaluation will compare two programs affecting part diameter. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Assign the better-performing block to one treatment and the other block to the second treatment.
B. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
C. Randomly sample a population but let participants choose treatments.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: B

At the regional manufacturer in New England network during a yearly program evaluation, group the parts by baseline score, then randomly assign units within each block to the two programs affecting part diameter. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 32. Randomized Experiments, Blocking, and Blinding

A county election office in Mountain Region during a two-month observation window will compare two programs affecting ballot-processing time. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Measure only one treatment because blocking removes the need for a control group.
D. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the county election office in Mountain Region during a two-month observation window, group the ballots by baseline score, then randomly assign units within each block to the two programs affecting ballot-processing time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 33. Randomized Experiments, Blocking, and Blinding

A housing authority in Sunbelt district during a randomized pilot period will compare two programs affecting application processing time. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Measure only one treatment because blocking removes the need for a control group.
C. Randomly sample a population but let participants choose treatments.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: A

At the housing authority in Sunbelt district during a randomized pilot period, group the applications by baseline score, then randomly assign units within each block to the two programs affecting application processing time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 34. Randomized Experiments, Blocking, and Blinding

A recycling program in Prairie District during a six-week field trial will compare two programs affecting weekly material weight. Describe a randomized design that uses baseline score as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Measure only one treatment because blocking removes the need for a control group.
C. Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation.
D. Assign the better-performing block to one treatment and the other block to the second treatment.

Answer: C

At the recycling program in Prairie District during a six-week field trial, group the households by baseline score, then randomly assign units within each block to the two programs affecting weekly material weight. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by baseline score, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 35. Randomized Experiments, Blocking, and Blinding

A community college in South Harbor during a quarterly performance study will compare two programs affecting course completion. Describe a randomized design that uses age group as a block and explain the benefit.

A. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.
B. Randomly sample a population but let participants choose treatments.
C. Assign the better-performing block to one treatment and the other block to the second treatment.
D. Measure only one treatment because blocking removes the need for a control group.

Answer: A

At the community college in South Harbor during a quarterly performance study, group the enrolled learners by age group, then randomly assign units within each block to the two programs affecting course completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice D: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Question 36. Randomized Experiments, Blocking, and Blinding

A school district in Mountain Region during a randomized pilot period will compare two programs affecting lunch-program participation. Describe a randomized design that uses age group as a block and explain the benefit.

A. Randomly sample a population but let participants choose treatments.
B. Assign the better-performing block to one treatment and the other block to the second treatment.
C. Measure only one treatment because blocking removes the need for a control group.
D. Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation.

Answer: D

At the school district in Mountain Region during a randomized pilot period, group the students by age group, then randomly assign units within each block to the two programs affecting lunch-program participation. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

Why the other choices fail

Choice A: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice B: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.
Choice C: It does not match the requested calculation. The correct comparison or result is: Block by age group, randomize treatments within each block, and compare responses; this controls block-to-block variation. Key check: Blocking reduces unexplained variation; blinding limits measurement or expectation bias.

Randomized Experiments, Blocking, and Blinding free-response practice

10-point analytic study rubric used for the sets below
Evidence	Points
Correct target, notation, direction, or group order	2
Correct method/model and defensible conditions	2
Correct setup and execution	3
Contextual interpretation and scope/limitation	2
Clear communication with units and labels	1

FRQ set 1: Randomized Experiments, Blocking, and Blinding

Scenario. A community bank in South Harbor during a quarterly performance study will compare two programs affecting mobile-deposit adoption. Describe a randomized design that uses previous experience as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the community bank in South Harbor during a quarterly performance study, group the customers by previous experience, then randomly assign units within each block to the two programs affecting mobile-deposit adoption. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 2: Randomized Experiments, Blocking, and Blinding

Scenario. A public high school in Metro East during a spring 2027 pilot will compare two programs affecting algebra benchmark completion. Describe a randomized design that uses site as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the public high school in Metro East during a spring 2027 pilot, group the students by site, then randomly assign units within each block to the two programs affecting algebra benchmark completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 3: Randomized Experiments, Blocking, and Blinding

Scenario. A grocery cooperative in Mountain Region during a yearly program evaluation will compare two programs affecting checkout time. Describe a randomized design that uses site as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the grocery cooperative in Mountain Region during a yearly program evaluation, group the customers by site, then randomly assign units within each block to the two programs affecting checkout time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 4: Randomized Experiments, Blocking, and Blinding

Scenario. A grocery cooperative in North Valley during a summer implementation review will compare two programs affecting checkout time. Describe a randomized design that uses baseline score as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the grocery cooperative in North Valley during a summer implementation review, group the customers by baseline score, then randomly assign units within each block to the two programs affecting checkout time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 5: Randomized Experiments, Blocking, and Blinding

Scenario. A university advising center in Pacific Northwest during a monthly quality review will compare two programs affecting appointment wait time. Describe a randomized design that uses previous experience as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the university advising center in Pacific Northwest during a monthly quality review, group the appointments by previous experience, then randomly assign units within each block to the two programs affecting appointment wait time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 6: Randomized Experiments, Blocking, and Blinding

Scenario. A regional manufacturer in North Valley during a regional benchmarking study will compare two programs affecting part diameter. Describe a randomized design that uses age group as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the regional manufacturer in North Valley during a regional benchmarking study, group the parts by age group, then randomly assign units within each block to the two programs affecting part diameter. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 7: Randomized Experiments, Blocking, and Blinding

Scenario. A wildlife clinic in Atlantic Corridor during a school-year data collection will compare two programs affecting recovery time. Describe a randomized design that uses baseline score as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the wildlife clinic in Atlantic Corridor during a school-year data collection, group the animals by baseline score, then randomly assign units within each block to the two programs affecting recovery time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 8: Randomized Experiments, Blocking, and Blinding

Scenario. A city recreation department in Prairie District during a pre-exam training cycle will compare two programs affecting program satisfaction. Describe a randomized design that uses site as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the city recreation department in Prairie District during a pre-exam training cycle, group the participants by site, then randomly assign units within each block to the two programs affecting program satisfaction. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with site, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 9: Randomized Experiments, Blocking, and Blinding

Scenario. A recycling program in Desert County during a spring 2027 pilot will compare two programs affecting weekly material weight. Describe a randomized design that uses previous experience as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the recycling program in Desert County during a spring 2027 pilot, group the households by previous experience, then randomly assign units within each block to the two programs affecting weekly material weight. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 10: Randomized Experiments, Blocking, and Blinding

Scenario. A regional airport authority in Westview during a service-improvement study will compare two programs affecting security wait time. Describe a randomized design that uses previous experience as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the regional airport authority in Westview during a service-improvement study, group the travelers by previous experience, then randomly assign units within each block to the two programs affecting security wait time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 11: Randomized Experiments, Blocking, and Blinding

Scenario. A public high school in Coastal Plains during a follow-up evaluation period will compare two programs affecting algebra benchmark completion. Describe a randomized design that uses previous experience as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the public high school in Coastal Plains during a follow-up evaluation period, group the students by previous experience, then randomly assign units within each block to the two programs affecting algebra benchmark completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 12: Randomized Experiments, Blocking, and Blinding

Scenario. A community bank in New England network during a follow-up evaluation period will compare two programs affecting mobile-deposit adoption. Describe a randomized design that uses previous experience as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the community bank in New England network during a follow-up evaluation period, group the customers by previous experience, then randomly assign units within each block to the two programs affecting mobile-deposit adoption. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with previous experience, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 13: Randomized Experiments, Blocking, and Blinding

Scenario. A digital learning platform in Mountain Region during a service-improvement study will compare two programs affecting lesson completion. Describe a randomized design that uses age group as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the digital learning platform in Mountain Region during a service-improvement study, group the learners by age group, then randomly assign units within each block to the two programs affecting lesson completion. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with age group, which can improve precision; random assignment supports a causal comparison for these experimental units.

FRQ set 14: Randomized Experiments, Blocking, and Blinding

Scenario. A wildlife clinic in Midwest consortium during a multiweek validation study will compare two programs affecting recovery time. Describe a randomized design that uses baseline score as a block and explain the benefit.

Identify the observational units, population, treatments or sampling frame, and the design goal.
Describe the selection or assignment mechanism precisely enough that another researcher could implement it.
Explain how the design controls bias, confounding, or variability, and identify a remaining limitation.
State the scope of inference: population generalization, causal conclusion, both, or neither.

Model response

At the wildlife clinic in Midwest consortium during a multiweek validation study, group the animals by baseline score, then randomly assign units within each block to the two programs affecting recovery time. Keep other conditions as similar as practical and compare responses. Blocking controls variation associated with baseline score, which can improve precision; random assignment supports a causal comparison for these experimental units.