Exam Strategy

Statistics · AP · Collecting Data

CED focus

Introduction to Experimental Design

This topic is assessed on the AP Exam.

Multiple-choice tips

• Identify whether the stem allows causal claims.
• Identify observational vs experiment in the stem.
• Eliminate causal language from observational designs.
• Match sampling method vocabulary (SRS, stratified, cluster).
• Spot voluntary response and convenience bias in MC.

Free-response tips

• Name population, sample, and what was randomized.
• Name population, sample, and treatment in words.
• Explain how randomization supports inference.
• Identify confounding and how blocking might help.
• State whether causation is justified by the design.

Common traps

• Causal language from an observational study
• Claiming causation from an observational study
• Confusing stratified and cluster sampling
• Ignoring confounding when comparing groups

Quick checklist

• [ ] Can name the sampling or experimental design
• [ ] Can explain why randomization matters
• [ ] Can state whether causation is supported