Invariance of factor structure of the 21-item Peters et al. Delusions Inventory (PDI-21) over time and across samples

The present study aimed to explore the latent structure of the 21-item Peters et al. Delusions Inventory (PDI-21) and to test the invariance of its factor structure over time and across samples. The PDI-21 was administered in two samples; one consisting of 1655 undergraduate students investigated in three waves, each separated by six months; and another consisting of 196 outpatients with schizophrenia. Exploratory factor analysis was performed...