Chapter 12, Problem 12E

To determine

To identify for the following reports about the statistical studies, the population, the population parameter of interest, the sampling frame, the sample, the sampling method including whether or not randomized was employed and any potential sources of bias you can detect and any problems you see in generalizing to the population of interest.

Explanation of Solution

It is given in the question that state police set up a roadblock to estimate the percentage of cars with up-to-date registration, insurance, and safety inspection stickers. They usually find problems with about $10\%$ of the cars they stop. Thus, from this report we can identify that:

The population will be: Cars.

The population parameter of interest will be: Proportion with up-to-date registration, insurance, and safety inspections.

The sampling frame will be: All cars on the road.

The sample is: Cars stopped by roadblock.

The sampling method including whether or not randomized was employed is: It is Cluster sample of location, census within cluster.

Any potential sources of bias you can detect and any problems you see in generalizing to the population of interest: Time of day and location may not be representative of all cars.