An item-factor analysis of the Eysenck Personality Questionnaire (E.P.Q.): Will the real personality factors stand up

The study utilised responses to the E.P.Q. from 3 samples of subjects. An initial sample of 239 Independent Study Students, a second sample of 278 student and pupil nurses and an aggregate sample of 617 students of both types. The samples were subjected to principal components analyses followed by varimax and promax rotations. Scree Test, number of significant loadings, replicability across samples and sexes, factor reliability and factor replicability were used as criterion measures to determine the number of real factors present. Nearly all the N, E and L-items were recovered in the analyses of each of the samples. In the two smaller samples, insufficient items were retrieved to indicate the presence of a clear psychoticism factor, but in the aggregate sample one factor contained 19 of the 25 P-items. Scree Test, numbers of significant loadings, replicability over samples and factor reliability criteria indicated that either a 4- or 5-factor solution was a valid possibility. Application of the criterion of factor replicability, using factor comparability coefficients based on factor scores, revealed an exceptionally clear 4-factor structure which was also replicable across sexes. The effects of dissimulation were investigated by dichotomising the male and female samples by L-scores. In both cases the mean scores for P and N for the low L-score group were higher than the corresponding mean scores for the high L-score group, which supports a previous finding that dissimulation tends to artificially lower the P and N-scores. Examination of the effect of dissimulation on the factor structure showed that E and N came out equally clearly in the high and low L-score groups for both males and females. P came out more clearly in the low L-score group for males and in the high L-score group for females, the latter finding being contrary to that of other authors. The investigation confirmed the presence of 4 “real”, replicable factors of P, E, N and L at the first order, showed that P and N are sensitive to dissimulation and illustrated the effectiveness of using factor replicability, measured by factor comparability coefficients based on factor scores, to determine the number of “real” factors in an analysis.