TEST OF DIFFERENCE BETWEEN PROPORTIONS
A social psychologist is interested in how personality characteristics are expressed in the car someone drives. In particular she
wonders whether men express a greater need for control than women by driving big cars. She takes a sample of 200 males and 200
females over the age of 18 and determines whether they drive a fullsized car. Any respondent who does not own a car is thrown out of
the samples but not replaced by someone else. Therefore the sample sizes for each group are not quite 200. The following hypothesis
concern the population proportion of men with big cars (π
1
) and the population proportion of women with big cars (π
2
):
Null hypothesis or H
0
: The population proportions of men and women who drive big cars are equal
π
1
= π
2
Research hypothesis or H
1
: The population proportions of men and women who drive big cars are not equal
π
1
≠ π
2
We are looking for an alpha level α=.05
The social psychologist obtains the following data:
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This note was uploaded on 07/13/2011 for the course SOC 301 taught by Professor Heberle during the Spring '11 term at University of Louisville.
 Spring '11
 Heberle

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