AP Statistics · Topic 3.2
Introduction to Planning a Study Practice
Part of Collecting Data.(DAT-2.A)
Practice questions
10
Sample questions
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Sample 1difficulty 1/5
A researcher randomly divides 50 mice into two groups, feeds one a high-fat diet and the other a standard diet, and measures weight gain after 8 weeks.
Which best describes this study?
- A
A blocked experiment
- Bcheck_circle
A completely randomized experiment
- C
An observational study
- D
A matched-pairs experiment
Why
Treatments are imposed and randomly assigned with no blocking - a completely randomized experiment.
- A
Sample 2difficulty 1/5
A census measures
- A
Only volunteers
- B
Only experimental subjects
- Ccheck_circle
Every individual in the population
- D
A random sample
Why
Census = complete enumeration of population.
- A
Sample 3difficulty 1/5
A nutritionist follows 500 adults for 10 years, recording their self-reported coffee consumption and tracking heart-disease incidence. She does not assign any participant to drink or avoid coffee.
This study is best described as
- A
A matched-pairs experiment
- Bcheck_circle
An observational study
- C
A randomized experiment
- D
A blocked experiment
Why
No treatment is imposed by the researcher; she merely observes existing coffee habits and outcomes. This is an observational study.
- A
Sample 4difficulty 2/5
Researchers select a random sample of 200 employees from a large company and randomly assign 100 to a new flexible-schedule policy and 100 to the standard schedule. After 6 months they compare productivity.
Which scope of inference is appropriate?
- A
Generalization only, no causal inference
- Bcheck_circle
Cause-and-effect can be inferred and results generalized to all employees of the company
- C
Neither causal inference nor generalization
- D
Cause-and-effect inference only, no generalization
Why
Random sampling allows generalization to the population (the company); random assignment allows causal inference. Both random elements are present, so both conclusions are justified.
- A
Sample 5difficulty 2/5
The most common practical reason for using a sample over a census is
- A
It is required by law
- Bcheck_circle
Cost and time
- C
Lack of population
- D
Sampling is biased on purpose
Why
Censuses are usually expensive and time-consuming; samples are quicker and cheaper.
- A