parameters (ab), which were tested along with other path coefficients in the model, provided a test of indirect effects. MODEL CONSTRAINT is the recommended method for estimating indirect effects in Mplus in the context of multiple imputation (Muthén & Muthén, 1998–2012). The estimation of indirect effects via the MODEL CONSTRAINT command uses the delta method (MacKinnon, 2008) that takes into account the covariance between the a and b estimates and provides estimates of standard errors for the indirect effects.
