Collecting Data, Sampling, and Experiments
This topic tests sampling design, bias, experiments, random assignment, blocking, matched pairs, blinding, controls, ethics, and scope of inference.
How to study for AP Statistics
Build every answer around the statistical question, data source, model, conditions, calculation, and contextual conclusion before writing the final inference.
Core concepts
Concept 1
Collecting data questions decide what conclusions are justified by design.
Exam cue: Identify population, sample, units, treatments, and response variable.
Concept 2
Random sampling supports generalization; random assignment supports cause and effect.
Exam cue: Ask whether random sampling, random assignment, both, or neither occurred.
Concept 3
Bias and confounding must be addressed before trusting conclusions.
Exam cue: State conclusion limits based on the design.
Risk pitfalls and guardrails
Confusing random sampling with random assignment.
Guardrail: Avoid answers that rely only on habit, ignore the stated source, skip safety or compliance steps, or choose convenience over the professional standard.
Claiming causation from an observational study.
Guardrail: Avoid answers that rely only on habit, ignore the stated source, skip safety or compliance steps, or choose convenience over the professional standard.
Ignoring nonresponse, undercoverage, wording bias, or confounding.
Guardrail: Avoid answers that rely only on habit, ignore the stated source, skip safety or compliance steps, or choose convenience over the professional standard.
Memory anchors
Population
A population is the entire group of interest.
Sample
A sample is the subset of individuals measured.
Random Sample
A random sample uses chance to select individuals from a population.
Bias
Bias is systematic error that favors some outcomes.
Experiment
An experiment imposes treatments to measure effects.
Random Assignment
Random assignment uses chance to assign treatments in an experiment.
Control Group
A control group provides a comparison for treatment effects.
Blocking
Blocking groups similar experimental units before random assignment.
Blinding
Blinding hides treatment information to reduce response or measurement bias.
Scope of Inference
Scope of inference states whether conclusions can generalize or infer causation.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
A population is:
A sample is:
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
What is Pass Harbor?
Completely free exam prep for 317 U.S. exams.
- Practice questions
- Flashcards
- Study guides
- Mock exams
- No registration
- No paywall
- Start instantly
“No more expensive exam prep. Quality study tools should be accessible to everyone.”