Inferential errors in taxometric analyses of ordered three-class constructs.

Taxometric analysis (Waller & Meehl, 1998) has become a popular tool for investigating whether personality and psychopathology constructs are better modeled as dimensional or categorical. Monte Carlo evidence for the validity of taxometric methods, however, has been restricted to data that are derived either from latent dimensional or dichotomous models. There are various circumstances in which the correct model for a psychosocial construct could involve three or more ordered classes. It was demonstrated both mathematically and empirically that under these circumstances, the results of taxometric analyses can lead to incorrect conclusions about the population structure. Recommendations are provided for future studies intended to distinguish between categorical and dimensional structures.