This zip-file contains the Mx scripts to fit the univariate and multivariate GxE models from the paper:

Dylan Molenaar, Sophie van der Sluis, Dorret I. Boomsma, & Conor V. Dolan (2012). Detecting Specific Genotype by Environment Interaction using Marginal Maximum Likelihood Estimation in the Classical Twin Design. Behavior Genetics, 42, 483-499.

In addition, to decrease the length of the paper, we included only a multivariate application in the final version of the paper. Here you can find a short report on an univariate application of the GxE model.

Non-normality in the Graded Response Model

This file contains the Mx script to fit the Heteroscedastic Graded Response Model with Skewed Latent Trait. See the following paper:

Dylan Molenaar, Conor V. Dolan, & Paul de Boeck (2012). The Heteroscedastic Graded Response Model with a Skewed Latent Trait: Testing Statistical and Substantive Hypotheses related to Skewed Item Category Functions. Psychometrika, 77, 455-478.

Non-normality in the second-order factor model

This file contains Mx-code to fit a second-order factor model with 1) non-linear second-order factor loadings, and/or heteroscedastic residuals. 2) a skew-normally distributed second-order factor, and/or heteroscedastic residuals.

This file accompanies the paper:

Dylan Molenaar, Conor V. Dolan, & Han L.J. van der Maas (2011). Modeling ability differentiation in the second-order factor model. Structural Equation Modeling, 18 , 578-594.

Moderated factor analysis

This file contains Mx-code to fit a moderated second-order factor model.

This file accompanies the paper:

Dylan Molenaar, Conor V. Dolan, Jelte M. Wicherts, & Han L.J. van der Maas (2010). Modeling Differentiation of Cognitive Abilities within the Higher-Order Factor Model using Moderated Factor Analysis. Intelligence, 38, 611-624.

For any question regarding these scripts, please send a message to d.molenaar [at] uva [dot] nl.

Non-normality within the One Factor Model

The following files accompany the paper:

Dylan Molenaar, Conor Dolan, & Norman Verhelst (2010). Testing and modeling non-normality within the one factor model. British Journal of Mathematical and Statistical Psychology, 63, 293-317.