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Psychometric measurement of personality as it is applied today is very problematic and often results in unreliable, invalid prediction. The main problems have been, on one hand, the number of personality traits and on the other hand, the almost exclusive use of subjective self-report inventories (Q-data) that more or less automatically lead to biased or distorted judgments. The former problem no doubt is the reason for the popularity of the so-called "Big Five" personality dimensions. There are, however, strong reasons for questioning their validity. In order to remedy the latter problem, more research is needed to develop objective test (T-data) instruments similar, for example, to Cattell's Objective-Analytic Battery.
This document has been peer reviewed.