Mplus Users Guide v6.. - Muthén & Muthén

CHAPTER 8algorithm will be used. Note that numerical integration becomesincreasingly more computationally demanding as the number of factorsand the sample size increase. In this example, two dimensions ofintegration are used with a total of 225 integration points. TheESTIMATOR option of the ANALYSIS command can be used to selecta different estimator.In the parameterization of the growth model shown here, the thresholdsof the outcome variable at the four time points are held equal as thedefault. The intercept of the intercept growth factor is fixed at zero inthe last class and is free to be estimated in the other classes. Theintercept of the slope growth factor and the residual variances of theintercept and slope growth factors are estimated as the default, and thegrowth factor residual covariance is estimated as the default because thegrowth factors do not influence any variable in the model except theirown indicators. The intercepts of the growth factors are not held equalacross classes as the default. The residual variances and residualcovariance of the growth factors are held equal across classes as thedefault. An explanation of the other commands can be found inExample 8.1.EXAMPLE 8.5: GMM FOR A COUNT OUTCOME USING AZERO-INFLATED POISSON MODEL AND A NEGATIVEBINOMIAL MODEL WITH AUTOMATIC STARTING VALUESAND RANDOM STARTSTITLE: this is an example of a GMM for a countoutcome using a zero-inflated Poissonmodel with automatic starting values andrandom startsDATA: FILE IS ex8.5a.dat;VARIABLE: NAMES ARE u1–u8 x;CLASSES = c (2);COUNT ARE u1-u8 (i);ANALYSIS: TYPE = MIXTURE;STARTS = 20 2;STITERATIONS = 20;ALGORITHM = INTEGRATION;208