Units 3–4: Statistical Inference

Understand what a confidence interval estimates, how its margin of error is formed, and how to interpret confidence correctly in context.

Confidence interval formula and calculator guide covering method choice, standard errors, critical values, conditions, and worked examples.

Margin of error and confidence level guide covering sample size, critical values, precision trade-offs, formulas, examples, and practice.

Build a significance test from the statistical question outward: define the parameter, write hypotheses, verify the procedure, measure evidence, and make a contextual conclusion without overstating what the data prove.

Translate a research claim into hypotheses about a population parameter, put equality in the null hypothesis, choose the alternative direction before seeing the data, and keep sample statistics out of the hypotheses.

Separate three linked but different ideas: the test statistic measures how far the sample result is from the null model, the p-value measures tail evidence under that model, and alpha supplies the decision threshold.