Evaluating the Internal Structure of the Eysenck Personality Questionnaire: Objective Criteria

Controversy over the internal structure of personality inventories has centered on appropriate methodology and has often been based on differing criteria among researchers. Much of this controversy has revolved in particular around the Eysenck Personality Questionnaire (EPQ) or other Eysenck tests. An approach based on targeted rotations and the test's scoring key is proposed as a means of providing common criteria. These are based on the number of items having their highest loading on their keyed scale, the mean loading of keyed items and the number of items having their highest loading on non-keyed scales. Several data sets from earlier studies are analyzed, together with a new set based on the responses to the EPQ of 195 undergraduates, using the proposed criteria. Results were very similar across samples and suggested specific weaknesses with two EPQ scales. This provided support for the utility of the three criteria.