Family Overview

Statistics · AP · Collecting Data

What this topic is

In Statistics · AP, this CED topic focuses on: Introduction to Planning a Study. In plain terms, students should be able to explain the main idea in their own words and complete a straightforward practice item with justification.

This topic is assessed on the AP Exam.

Why it matters

• Collecting data (sampling and experiments) determines whether conclusions are valid.
• AP Stats rewards clear language: population, sample, treatment, blocking, blinding.
• Bias and confounding are free-response gold when explained in context.
• Randomization is the key idea connecting design to later inference.

How you can support

• Ask: “Was this an observational study or an experiment—and why does that matter?”
• Have them name the population and the sampling method in one breath.
• Praise identifying a possible bias and how it could distort results.
• Ask how randomization (of sample or treatments) helps.
• For experiments, ask what was compared and what was controlled.

What not to do

• Do not claim causation from an observational study.
• Do not confuse voluntary response with a simple random sample.
• Do not skip explaining confounding when two variables are tangled.
• Do not treat “random” as a magic word without saying what was randomized.