Chapter 12, Problem 14E

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 dairy inspectors visit farms unannounced and take samples of the milk to test for contamination. If the milk is found to contain dirt, antibiotics or other foreign matter the milk will be destroyed and the farm re-inspected until purity is restored. Thus, from this report we can identify that:

The population will be: Dairy farms.

The population parameter of interest will be: Proportion passing inspection.

The sampling frame will be: It is unclear, possibly all dairy farms.

The sample is: It is unclear from the report.

The sampling method including whether or not randomized was employed is: It is Multistage sampling.

Any potential sources of bias you can detect and any problems you see in generalizing to the population of interest: Are farms and the milk at each farm randomly selected?