AP Stats Stats: Evaluation Content and Structure 2 — Questions and Answers
Question 1: A researcher surveys every 10th student on an alphabetical class roster. What type of sampling method is this?
- Simple random sampling
- Systematic sampling (Correct answer)
- Stratified sampling
- Cluster sampling
Correct answer: Systematic sampling
Systematic sampling selects every kth element from an ordered list after a random start.
Question 2: Which of the following best describes a confounding variable in an experiment?
- A variable that is deliberately manipulated by the researcher
- A variable that is the primary response being measured
- A variable related to both the explanatory and response variable that can distort results (Correct answer)
- A variable that has no effect on the outcome of the study
Correct answer: A variable related to both the explanatory and response variable that can distort results
A confounding variable is associated with both the explanatory variable and the response, making it hard to determine causation.
Question 3: In an observational study comparing incomes of college graduates vs. non-graduates, why can't we conclude that college causes higher income?
- The sample size is too small
- There is no way to measure income accurately
- Lurking variables such as family background may explain the difference (Correct answer)
- Observational studies always have measurement error
Correct answer: Lurking variables such as family background may explain the difference
Observational studies cannot establish causation because lurking variables may drive any observed association.
Question 4: A study randomly assigns participants to treatment and control groups. This design feature primarily controls for:
- Sampling bias
- Non-response bias
- Confounding variables (Correct answer)
- Undercoverage
Correct answer: Confounding variables
Random assignment balances both known and unknown confounding variables across treatment groups.
Question 5: Which of the following is an example of a double-blind experiment?
- Neither the subjects nor the researchers know who received which treatment (Correct answer)
- Only the subjects do not know which treatment they received
- Only the researchers do not know which treatment was given
- Both groups receive the same treatment
Correct answer: Neither the subjects nor the researchers know who received which treatment
Double-blind means both participants and those measuring outcomes are unaware of treatment assignments.
Question 6: A poll asking 'Don't you agree that texting while driving is dangerous?' is an example of:
- Undercoverage
- Response bias due to leading question wording (Correct answer)
- Non-response bias
- Voluntary response bias
Correct answer: Response bias due to leading question wording
The phrasing 'Don't you agree' leads respondents toward a particular answer, causing response bias.
Question 7: A study finds a strong positive correlation (r = 0.92) between shoe size and reading scores in elementary students. The most plausible explanation is:
- Larger feet cause better reading ability
- Better readers cause their feet to grow faster
- Age is a lurking variable explaining both (Correct answer)
- The correlation coefficient was calculated incorrectly
Correct answer: Age is a lurking variable explaining both
Older children have both larger feet and higher reading scores, making age the lurking variable driving this correlation.
AP Stats Stats: Evaluation Content and Structure 2
A researcher surveys every 10th student on an alphabetical class roster.
What type of sampling method is this?