Mplus Users Guide v6.. - Muthén & Muthén

CHAPTER 14• User-specified starting values for mixture models• Multiple solutions for mixture models• Convergence problems• Model identification• Numerical integrationPARAMETER DEFAULT SETTINGSDefault settings are used to simplify the model specification. In order tominimize the information provided by the user, certain parameters arefree, constrained to be equal, or fixed at zero as the default. Thesedefaults are chosen to reflect common practice and to avoidcomputational problems. These defaults can be overridden. Because ofthe extensive default settings, it is important to examine the analysisresults to verify that the model that is estimated is the intended model.The output contains parameter estimates for all free parameters in themodel, including those that are free by default and those that are freebecause of the model specification. Parameters that are fixed in theinput file are also listed with these results. Parameters fixed by defaultare not included. In addition, the TECH1 option of the OUTPUTcommand shows which parameters in the model are free to be estimatedand which are fixed.Following are the default settings for means/intercepts/thresholds in themodel when they are included:• Means of observed independent variables are estimated as or fixed atthe sample values when they are included in the model estimation.• In single group analysis, intercepts and thresholds of observeddependent variables are free.• In multiple group analysis and multiple class analysis, intercepts andthresholds of observed dependent variables that are used as factorindicators for continuous latent variables are free and equal acrossgroups or classes. Otherwise, they are free and unequal in the othergroups or classes except for the inflation part of censored and countvariables in which case they are free and equal.• In single group analysis, means and intercepts of continuous latentvariables are fixed at zero.• In multiple group analysis and multiple class analysis, means andintercepts of continuous latent variables are fixed at zero in the first408