Identifying fraudulent questionnaires Questionaires are often used in social sciences.
Many people try to complete them very quickly and very often they only "guess" answers.
Is there any statistical technique or any research in this area, how to identify which questionnaires are completed poorly?
I think that this is similar to detection of outliers, but which technique is the most relevant? Some persons have very strange behaviour, so they would be identified as outliers although their questionnaires are not fraudulent.
So how to distinguish between fraudulent questionnaire and very strange person?
I have already tried to identify fraudulent questionnaires but they claimed that they were only unique persons :-).
 A: This is a fairly large topic in social psychology and questionnaire design.  Here are some ideas:


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*The person could be faking it, either good or bad. People do this in order to appear "good" to the person doing the study. There are scales to detect this sort of faking, such as the Crowne=Marlowe scale.  These essentially ask questions to which virtually no one could answer "yes" (e.g. "I have never told a lie in my life").

*Often, people designing questionnaires will ask the same question in different ways. One well-known issue is that people will give different age answers if you ask "How old are you?" and "What is your birth date?"  The latter have been found to be more accurate.

*Another type of pattern is to answer all the questions with one answer on multiple choice questionnaires.  One way to detect this is to have some questions that are reverse coded. Then someone who answers (say) "nearly all the time" to both "I am happy" and "I am sad" may be suspect.

*You can also look at correlations among the questions and then identify people who have very different patterns.
Of course, none of these are fool-proof. But they are ways to investigate the issue.
