CHAPTER 8

Design of a Study: Sampling, Surveys, and

Experiments

1. 
   

        Medical researchers are conducting  a   study   on  a   new blood   pressure    medication. There   are three

   
   

   treatment groups: one receives the new drug, one receives the current most widely used medication,
   and a control group receives a placebo. The purpose of the control group is
   (A) to ensure that the test results are significant.
   (B) to eliminate bias.
   (C) to reduce confounding.
   (D) to see whether either drug is better than doing nothing.
   (E) to make sure the comparison of the new drug to the current drug is statistically valid.

   
   


2. Administrators of a large high school want to survey the student body. Rather than use a simple
   random sample of students, they want to do a stratified random sample, stratifying by either grade or
   gender. It would be more advantageous to stratify by grade than by gender if
   (A) there is a larger difference of opinion between students of different genders than between
   students of different grades.
   (B) there is a larger difference of opinion between students of different grades than between students
   of different genders.
   (C) students of different grades have pretty much the same opinion on the topic.
   (D) students of one gender are more likely to be dishonest when answering the question.
   (E) a simple random sample of each grade is easier to collect than a simple random sample of each
   gender.


3. Which statement correctly describes a difference between simple random sampling and stratified
   random sampling?
   (A) Simple random sampling is less biased than stratified random sampling.
   (B) Stratified random sampling is less biased than simple random sampling.
   (C) Stratified random sampling always has less variability between different samples than simple
   random sampling.
   (D) Stratified random sampling has less variability between different samples than simple random