Saturday, April 16, 2011

Comments on SIOP 2011: Faking on personality tests

The issue of faking is alive and well. Several sessions at the 2011 SIOP are devoted to it. Nobody or very few deny that faking occurs and that it can affect the outcome of a test, sometimes severely so. It is also realized that faking greatly hurts the credibility of personality testing. Non-experts test users simply are convinced that the test takers often fake good in a high-stakes situation, such as when they apply for a very desirable job or admittance to a prestige school.

It is clear that faking reduces the validity of personality tests, if left uncorrected. The effect can be very substantial. Meta analyses of the validity of personality tests tend to be based on data from incumbents, since job performance (criterion) data cannot normally be obtained from all applicants, and applicant scores are only correlated about 0.5 with incumbent scores. Hence, faking makes the data used in meta analyses of doubtful relevance to the question of test validity.

The most important of the Big Five factors, conscientiousness, is the one most affected by faking. It is also clear that the group of fakers, while heterogeneous, may contain some people who are risky to hire. Ignoring faking comes with great risks for the test users.

What can be done?A powerful alternative is to measure social desirability (SD) and use and SD scale to correct other scales for faking, to the extent hat they correlate with SD (not all scales do and correlations vary strongly in the typical case).The procedure has been validated both in experimental and field work.

There are a few objections, however.

1. SD scales are said to measure "personality". It is somewhat unclear what this means and why it is an argument. SD scales to have correlates with many other dimensions and they also have a certain amount of consistency over time and situations. So what? They can still measure faking at any given time.

2. There are several SD scales and they do not measure the same thing. The best known scales do have high intercorrelations, however.

3. You cannot detect who is a faker. Well, you can to some extent, albeit not perfectly, but who said that psychometrics ever comes up with perfect solutions?

4. Some people fake bad. This can be detected, but is not a major problem. Few people fake bad in  a high-situations where they have applied for a desirable job.

Some commercial test suppliers and their agents try to solve the problem of faking by denying that it exists. This is not a credible statement. Since the future of personality testing is probably dependent on there being a solution to the faking problem - why not use the solution described here? It works.

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