Reliability generalization of the Junior Eysenck Personality Questionnaire

A reliability generalization was conducted on the Psychoticism (P), Extraversion (E), Neuroticism (N) and Lie (L) scales of the Junior Eysenck Personality Questionnaire (J-EPQ). Twenty-three studies provided data on 44 samples of children who had been administered the J-EPQ. Score reliability was found to vary significantly both between and within scales. N and L provided the most reliable scores (with median reliabilities of 0.80 and 0.79 respectively) followed by E (median reliability=0.73) and P (median reliability=0.68). Scale length was the best predictor of score reliability, but sample gender makeup, language of administration, and the amount of variation in the ages of children in each sample were also significant predictors of reliability for various J-EPQ scales. The results highlight the importance of considering reliability to be a property of scores for a particular group, as opposed to a property of a test generally.