had the choice to do it over again. This is most likely representative only of those parents who
were having a really bad day with their children when they decided to respond to the question.
In fact, a properly designed opinion poll a few months later found that more than 90% of
parents said they would have children if they had the chance to do it all over again.Wording Bias
Wording bias occurs when the wording of the question itself influences the response in a systematic way.
A number of studies have demonstrated that welfare gathers more support from a random sample of the
public when it is described as “helping people until they can better help themselves” than when it is
described as “allowing people to stay on the dole.”
example: Compare the probable responses to the following ways of phrasing a question.
(i) “Do you support a woman’s right to make medical decisions concerning her own body?”
(ii) “Do you support a woman’s right to kill an unborn child?”
It’s likely that (i) is designed to show that people are in favor of the right to choose abortion and that
(ii) is designed to show that people are opposed to the right to choose abortion. The authors of both
questions would probably argue that both responses reflect society’s attitudes toward abortion.
example: Two different Gallup Polls were conducted in Dec. 2003. Both involved people’s
opinion about the U.S. space program. Here is one part of each poll.
Poll A : Would you favor or oppose a new U.S. space program that would send astronauts to the
moon? Favor—53%; oppose—45%.
Poll B: Would you favor or oppose U.S. government spending billions of dollars to send
astronauts to the moon? Favor—31%; oppose—67%.
(source: http://www.stat.ucdavis.edu/~jie/stat13.winter2007/lec18.pdf )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 the 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