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Mplus Users Guide v6.. - Muthén & Muthén

Mplus Users Guide v6.. - Muthén & Muthén

Mplus Users Guide v6.. - Muthén & Muthén

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CHAPTER 5unit variance of the latent response variables underlying u1 and u2 asshown in the MODEL CONSTRAINT command. The denominator forthe heritability estimate is one with categorical outcomes because thelatent response variables have unit variances.The default estimator for this type of analysis is a robust weighted leastsquares estimator. The ESTIMATOR option of the ANALYSIScommand can be used to select a different estimator. With maximumlikelihood, logistic or probit regressions are estimated using a numericalintegration algorithm. Note that numerical integration becomesincreasingly more computationally demanding as the number of factorsand the sample size increase. An explanation of the other commands canbe found in Examples 5.1, 5.14, 5.19 and 5.21.EXAMPLE 5.23: QTL SIBLING MODEL FOR A CONTINUOUSOUTCOME USING PARAMETER CONSTRAINTSTITLE: this is an example of a QTL sibling modelfor a continuous outcome using parameterconstraintsDATA: FILE = ex5.23.dat;VARIABLE: NAMES = y1 y2 pihat;USEVARIABLES = y1 y2;CONSTRAINT = pihat;MODEL: [y1-y2] (1);y1-y2 (var);y1 WITH y2 (cov);MODEL CONSTRAINT:NEW(a e q);var = a**2 + e**2 + q**2;cov = 0.5*a**2 + pihat*q**2;y1y2pihat86

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