Unit 3: Collecting Data

In a stratified random sample, the population is divided into groups called strata, and then:

The purpose of random assignment in an experiment is to:

An observational study differs from an experiment in that an observational study:

Voluntary response samples are often biased because:

In a double-blind experiment:

Response bias in a survey can occur when:

A blocked experiment differs from a completely randomized experiment because blocks:

A cluster sample differs from a stratified sample in that:

A researcher divides a school into freshmen, sophomores, juniors, and seniors, then randomly selects 25 students from each group. What type of sampling is this?

A survey about exercise habits is conducted by only surveying people leaving a gym. This is an example of what type of bias?

In a well-designed experiment, what is the purpose of random assignment?

Which of the following distinguishes an experiment from an observational study?

A study finds that students who eat breakfast score higher on exams. However, students who eat breakfast also tend to get more sleep. In this case, sleep is a:

In a double-blind experiment, who knows which subjects receive the treatment and which receive the placebo?

In a simple random sample (SRS) of size n from a population of size N:

In an experiment, subjects are first grouped by gender and then randomly assigned to treatments within each group. This technique is called:

An online poll asks visitors to a website to vote on an issue. This is an example of:

Why is replication important in experimental design?

In a matched pairs experiment, each subject receives:

What type of sampling method did the researcher use?