ADDITIVE AND MULTIPLICATIVE METHOD EFFECTS IN APPLIED PSYCHOLOGICAL-RESEARCH - AN EMPIRICAL-ASSESSMENT OF 3 MODELS

Method effects can be additive (independent of trait correlations) or multiplicative (associated with trait correlations). This study is the first to empirically assess the relationship between the nature of me thod effects and the goodness-of-fit of different latent factor models . Specifically, we examined method effects in 17 published multitrait- multimethod data sets and evaluated the usefulness of confirmatory fac tor analysis, the direct product approach, and Marsh's correlated uniq ueness technique for modeling these effects. While each of the models fit some of the data sets well, Marsh's technique appeared to be gener ally more effective. Also, Campbell and O'Connell's slope index indica ted that additive models (confirmatory factor analysis and the correla ted uniqueness approach) were not more likely than a multiplicative mo del (the direct product model) to provide a good fit to data with addi tive method effects; nor did a multiplicative model provide a better f it than additive models when method effects were multiplicative.