Question

The Denver Police Department wants to know if Hispanic residents of Denver believe that the police use racial profiling when making traffic stops. A sociologist prepares several questions about the police. The police department chooses an SRS of 300 mailing addresses in predominantly Hispanic neighborhoods and sends a uniformed Hispanic police officer to each address to ask the questions of an adult living there.

a. What are the population and the sample?
b. Why are the results likely to be biased even though the sample is an SRS?

Answer 1

a) The population is all the Hispanic residents of Denver.

The sample is 300 adults which very visited by the officer.

b) The results are likely to be biased because the adults may be fearful of the Hispanic officer, may be intimidated by their presence and not want to tell how they really feel about this question.

Explanation:

This is a common statistic method.

If you want to estimate something about a big population, you select a random sample of the population, and estimate for the entire population.

For example, if you want to estimate the proportion of residents of Buffalo, New York, that are Buffalo Bills fans, you are going to ask, for example, 1000 Buffalo residents. The population is all the residents of Buffalo, New York. and the sample are the 1000 Buffalo residents.

However, if you send a Bills player to ask this question, people will try to make him happy, which could lead to a biased answer.

So, for this question

a. What are the population and the sample?

The population is all the Hispanic residents of Denver.

The sample is 300 adults which very visited by the officer.

b. Why are the results likely to be biased even though the sample is an SRS?

The results are likely to be biased because the adults may be fearful of the Hispanic officer, may be intimidated by their presence and not want to tell how they really feel about this question.