Exam Strategy

Statistics · AP · Inference for Quantitative Data — Means

CED focus

Justifying a Claim About a Population Mean Based on a Confidence Interval

This topic is assessed on the AP Exam.

Multiple-choice tips

• Match procedure to parameter and design before calculating.
• Choose t vs z and one- vs two-sample vs paired from the design.
• Eliminate procedures that ignore pairing when matched pairs.
• Check df and Normal conditions on t-procedure MC.
• Match μ vs μ_d language to the scenario.

Free-response tips

• Use State–Plan–Do–Conclude with conditions and context throughout.
• Identify paired vs two-sample structure in context.
• State parameter (μ, μ₁ − μ₂, μ_d) clearly.
• Show t-interval or t-test with conditions and conclusion.
• Discuss practical significance after statistical significance.

Common traps

• ‘Accept H₀’ wording or skipping conditions
• Using two-sample t when data are paired
• Using z procedures when σ is unknown
• Concluding about individuals instead of the mean

Quick checklist

• [ ] Can choose the correct t-procedure
• [ ] Can interpret a CI for a mean in context
• [ ] Can state conditions for t inference