A questionnaire for the measurement of paranoia/suspiciousness.

A 47-item Paranoia/Suspiciousness Questionnaire was developed on a non-psychiatric sample using modified items from several established scales of paranoia and related concepts. Factor analysis of the questionnaire identified five moderately correlated subscales labelled Interpersonal Suspiciousness/Hostility, Negative Mood/Withdrawal, Anger/Impulsiveness, Mistrust/Wariness and Perceived Hardship/Resentment. There were no significant difference between males and females on the questionnaire or any of the subscales. The full questionnaire and the subscales showed satisfactory internal consistency and test-retest reliability. Further research is needed to establish the scale as a useful diagnostic tool.