The brief symptom inventory and the positive and negative syndrome scale: discriminate validity between a self-reported and observational measure of psychopathology.

Concern within the literature has emerged from time to time arguing the poor validity of self-reported measures in psychopathology, namely, the reporting of psychotic experience. Although it is commonly believed that patients who have had a psychotic episode cannot accurately self-report their experience, very few studies have been conducted to measure the concordance between self-reported and observational measures of psychopathology using multivariate statistical techniques. Sixty-nine patients presenting their first psychotic episode were interviewed and assessed on the Positive and Negative Syndrome Scale (PANSS) and were asked to complete the Brief Symptom Inventory (BSI). By clustering symptom dimensions from the BSI into discriminate functions, the research demonstrated that these symptom dimensions could adequately classify high versus low scores on the PANSS subscales and total score. When the same clusters were entered into multivariate analysis of variance (MANOVA) models, they also demonstrated significant differences between high versus low observed symptomatology on the PANSS Positive and General Subscale Groups and Total Score Groups. The current findings shed some doubt on the supposition that those who experience psychosis are unable to report symptom dimensions that concord with those who observe the psychosis. It appears that models, operational definitions, and the language used in measuring psychopathology may differ significantly from those who experience the psychotic experience and those who observe it. Techniques such as multitrait multimethod are discussed as ways of overcoming these concerns.