P-Factor(s) for Youth Psychopathology Across Informants and Models in 24 Societies.

Objective: Although the significance of the general factor of psychopathology (p) is being increasingly recognized, it remains unclear how to best operationalize and measure p. To test variations in the operationalizations of p and make practical recommendations for its assessment, we compared p-factor scores derived from four models.

Methods: We compared p scores derived from principal axis (Model 1), hierarchical factor (Model 2), and bifactor (Model 3) analyses, plus a Total Problem score (sum of unit-weighted ratings of all problem items; Model 4) for parent- and self-rated youth psychopathology from 24 societies. Separately for each sample, we fitted the models to parent-ratings on the Child Behavior Checklist for Ages 6-18 (CBCL/6-18) and self-ratings on the Youth Self-Report (YSR) for 25,643 11-18-year-olds. Separately for each sample, we computed correlations between p-scores obtained for each pair of models, cross-informant correlations between p-scores for each model, and Q-correlations between mean item x p-score correlations for each pair of models.

Results: Results were similar for all models, as indicated by correlations of .973-.994 between p-scores for Models 1-4, plus similar cross-informant correlations between CBCL/6-18 and YSR Model 1-4 p-scores. Item x p correlations had similar rank orders between Models 1-4, as indicated by Q correlations of .957-.993.

Conclusions: The similar results obtained for Models 1-4 argue for using the simplest model - the unit-weighted Total Problem score - to measure p for clinical and research assessment of youth psychopathology. Practical methods for measuring p may advance the field toward transdiagnostic patterns of problems.