The structure of the Prodromal Questionnaire-16 (PQ-16) in a non-help-seeking youth population: Exploratory and confirmatory factor analyses study.

Abstract

The present study aimed to examine the structure of the Prodromal Questionnaire-16 (PQ-16) in a non-help-seeking youth population through exploratory and confirmatory factor analysis. Previous studies have not examined the structure of this self-report measure in this age group outside a clinical setting. Participants (n=1165) aged 11-19years were recruited to an epidemiological study of young people in Northern Ireland, and completed the PQ-16 alongside other measures. The dataset was split randomly in two for separate factor analyses. A polychoric correlation matrix was created and exploratory factor analysis was used to identify the optimal number of factors. In addition, based on previous studies, six models were tested through confirmatory factor analysis to determine best fit. A one-factor, 3 two-factor, a three-factor and a four-factor model were all tested. The exploratory factor analysis indicated a two-factor structure of the PQ-16 in this population, which we have labelled 'general unusual experiences' and 'hallucinations'. Confirmatory analysis indicated that the two-factor model identified through the exploratory analysis was the best fit for the data. The present study suggests that the structure of the PQ-16 may vary across age groups in non-clinical settings, and adds further support to the validity of the PQ-16 is a cost-effective, easy to administer self-report measure that is suitable for use in non-help-seeking populations as a screening tool for prodromal symptoms.