From an abbreviated version of the Eysenck Personality Questionnaire (EPQ), the items on the neuroticism and extraversion
scales were included in the questionnaire (Grayson, 1986). The full 90-item EPQ has previously been validated in
Norway (Eysenck & Tambs, 1990). In the present short version, each dimension consisted of 10 questions from the EPQ,
each scoring 0 or 1. When three or less answers were missing, the missing value was substituted with the sample mean on
that variable. Sum-scores ranging from zero to 10 for each variable were calculated. Cronbach’s alpha was 0.77 for
extraversion and 0.73 for neuroticism. The two measures were negatively correlated (r = -0.30).