Measuring Psychotic Experiences at Scale: An Item Response Theory Analysis of the Adolescent Psychotic-like Symptom Screener (APSS)

Resumen de los autores

The Adolescent Psychotic-like Symptom Screener (APSS) is widely used to screen adolescents for psychotic experiences (PEs), but there are few rigorous psychometric analyses of the instrument. In this study, we apply Item Response Theory (IRT) to APSS responses from a large sample of middle and high school students in Massachusetts (N = 17,315, 49\% male, mean age 15.6 years). We compare several polytomous IRT models, evaluate item and test functioning, test for differential item functioning (DIF) by age and sex, and examine demographic predictors of PEs. We find that the data are consistent with a unidimensional interpretation of the APSS, and a graded response model fits the data well. All items have high discrimination parameters, but thresholds are concentrated above the population mean. As a result, reliability is maximized about 1.5 standard deviations above the mean and is poor at low trait levels. We identify eight non-zero DIF terms across age and sex, although most effects are small in magnitude. Latent regression analyses show that older students and male students report slightly lower levels of PEs, with a modest sex-by-age interaction. To facilitate practical application, we include R code to generate IRT-based APSS scores in new data based on our calibrated item parameters. Our results support the use of the APSS as an efficient screener for identifying adolescents with elevated PEs who may benefit from further assessment, while cautioning that it is not well suited to distinguish participants with low PEs.

Áreas y palabras clave

Cómo citar (APA 7)

Gilbert, J., Himmelsbach, Z., DeTore, N. R., & Schuster, R. M. (2026). Measuring Psychotic Experiences at Scale: An Item Response Theory Analysis of the Adolescent Psychotic-like Symptom Screener (APSS). https://doi.org/10.31234/osf.io/4pv75_v1