AP Statistics Experimental Design and Random Assignment Quiz: 10 Questions with Explanations

A A randomized block designB A matched pairs designC A completely randomized designD An observational study

Subjects are randomly assigned to treatments with no blocks.

A It lets us generalize to a populationB It makes treatment groups similar on averageC It eliminates all variabilityD It guarantees significance

Random assignment balances the groups, so differences in response can be attributed to treatments.

A select a random sampleB eliminate the placebo effectC replace replicationD reduce variability by grouping similar units

Comparing treatments within blocks removes variation due to the blocking variable.

A Generalize to the populationB Cause and effect for the volunteers onlyC Neither generalization nor causationD Both generalization and causation

Random assignment supports causation; volunteering means the sample is not random.

A single-blindB observationalC double-blindD randomized block

Double-blind means both groups are blinded.

A a confounding variableB a blockC a placeboD the control

Confounding mixes effects so they cannot be separated.

A repeating the same unit onceB using a placeboC using a random sampleD using enough units in each treatment group

Many units per treatment reduce the effect of chance variation.

A an observational studyB an experimentC a block designD a matched pairs design

No treatments are imposed.

A receives only one treatment at randomB receives both treatments (in random order) or is paired with a similar subjectC is a volunteerD is not randomized

Pairing controls for differences between subjects.

A the difference is unlikely to be due to chance aloneB the difference is large in practiceC the sample is randomD the p-value is large

Significance is about how unlikely the result would be by chance.