A survey asked 2000 people whether or not they frequently exceed the speed limit. The collected data is summarized in the following contingency table. The goal is to determine if there is a difference in the population proportion that say “yes” when comparing those who are under 40 years in age to those who are at least 40 years in age.
Frequently Exceed the Speed Limit?
Age Yes No Total
Age under 40 600 (60%) 400 1000
Age 40 and above 450 (45%) 550 1000
Total 1050 950 2000
a. What is the response variable in this problem?
Their admission of speeding.
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.