Question

You work in a very large metropolitan police department and have been assigned to a committee to select new patrol cars. Three models are in contention.

The Dodge Charger

The Chevrolet Tahoe

The Ford Interceptor

Your initial testing determines that all three models meet your department’s basic needs and that they are all comparably priced. So, the final decision is really based on the personal preference of the officers.

You and the members of your committee send out a simple survey asking each officer to indicate which of the three models he or she prefers. This survey indicates the following.

Vehicles	Percent of officer preference
The Dodge Charger	45%
The Chevrolet Tahoe	42%
The Ford Interceptor	13%
Totals	100%

Given the closeness of officer preference between the Dodge Charger and Chevrolet Tahoe it will be important now to determine whether the differences in preference are statistically significant, i.e. not due to chance. You start with a hypothesis.

Hypothesis: The difference in officer preference between the Dodge Charger and Chevrolet Tahoe is statistically significant.

Answer the following questions.

1. At what level is the variable ‘officer preference’ measured (nominal, ordinal or scale)?

2. What type of hypothesis is this (association or difference)?

Answer 1

(1)

Correct option: scale

Explanation:

the variable ‘officer preference’ measured : scale

Reason: Officer preference is given as proportions, which is a quantitative variable.

(2)

Correct option: difference

Explanation:

2 Samples Z Test for Proportions

Reason: Here the significance of difference between the proportions 2 Samples : officer preference between the Dodge Charger and Chevrolet Tahoe is tested.