Friday, December 21, 2012

Norms - a crucial issuse in testing

Test norms need to be specific to the user and the test context. This should be obvious, still is often ignored, perhaps due to the expenses involved. What happens if norms are not specific?

1. A very important aspect is that of faking. Faking is abundant in job applicants. If norms are collected from incumbents or, even worse, the population at large, test scores can be grossly misleading. The reason is that many applicants fake and the distribution of their test scores is shifted towards a higher mean than for incumbents who fake very little or not at all. As a consequence, test scores for applicants will be systematically overestimated. In a stanine scale, the error could easily be 2 or 3 steps. This problem could be greatly mitigated by using a correction procedure using one or several scales for measuring the tendency to respond in a socially desirable manner. In our data, about 95 % of the effect is eliminated this way. Note, however, that the correction model must be scale specific since scales are usually not equally vulnerable to distortion.

2. Test scores may be strongly dependent on the organizational context. In some contexts, independences is not a desired trait and people will on the average have low scores on this trait. Another example is perseverance in the face of failure. If failure is rarely obvious, test takers will report low perseverance. For reasons such as these, norms need to be specific to the organizations.

It is not excessively demanding to construct specific norms, given modern IT technology, and the sample size need to be only as small as 300, or even in some cases 120. The first step is to realize the importance of specific norms, of norms corrected for impression management if they are based on incumbents or the population at large, and the fact that the sample size can be fairly small. In our practice we work with such norms, but many Swedish test providers seem unaware of the issue and that the problems can be solved with relatively modest resources.
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