Sampling Bias for AP Statistics (page 2)

By — McGraw-Hill Professional
Updated on Feb 5, 2011

Response Bias

Response bias arises in a variety of ways. The respondent may not give truthful responses to a question (perhaps she or he is ashamed of the truth); the respondent may fail to understand the question (you ask if a person is educated but fail to distinguish between levels of education); the respondent desires to please the interviewer (questions concerning race relations may well solicit different answers depending on the race of the interviewer); the ordering of the question may influence the response ("Do you prefer A to B?" may get different responses than "Do you prefer B to A?").

example: What form of bias do you suspect in the following situation? You are a school principal and want to know students' level of satisfaction with the counseling services at your school. You direct one of the school counselors to ask her next 25 counselees how favorably they view the counseling services at the school.

    solution: A number of things would be wrong with the data you get from such a survey. First, the sample is nonrandom—it is a sample of convenience obtained by selecting 25 consecutive counselees. They may or may not be representative of students who use counseling service. You don't know.
    Second, you are asking people who are seeing their counselor about their opinion of counseling. You will probably get a more favorable view of the counseling services than you would if you surveyed the general population of the school (would students really unhappy with the counseling services voluntarily be seeing their counselor?). Also, because the counselor is administering the questionnaire, the respondents would have a tendency to want to please the interviewer. The sample certainly suffers from undercoverage—only a small subset of the general population is actually being interviewed. What do those not being interviewed think of the counseling?

Practice problems for these concepts can be found at:

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