Published on *OpenMx* (http://openmx.psyc.virginia.edu)

By *Ahmed*

Created *10/29/2013 - 17:38*

Tue, 10/29/2013 - 17:38 — Ahmed [1]

Hi!

I would like to adjust for age in longitudinal setting of two time points. In the model I would like to adjust for age from the two time points in the model. I am not sure about the number of rows and columns to be specified in the matrix for age in OpenMX. To begin with I set up the mean and beta coefficient for age as follows:

# Matrix for expected Mean

mean <- mxMatrix( "Full", nrow=1, ncol=4, free=TRUE,

values= 1.6, label=c("meany11","meany12","meany11","meany12" ), name="expMeanGy" )

# Matrix for beta

beta <- mxMatrix( type="Full", nrow=1, ncol=4, free=TRUE,

values=.1, labels=c('b1','b2','b1','b2'), name="beta" )

I also specified the age as shown in below but I am not quite sure if this is the right way to go.

# Matrix for age - Mz twins

MZvaro <- mxMatrix(type="Full", nrow=2, ncol=2, free=TRUE,

values=.1, labels=c('data.agez11','data.age21, data.age12','data.age22,'), name="DefMZvaro")

Many thanks in advance!

Ahmed

**Links:**

[1] http://openmx.psyc.virginia.edu/users/ahmed

[2] http://openmx.psyc.virginia.edu/thread/2436

[3] http://openmx.psyc.virginia.edu/thread/1902

[4] http://openmx.psyc.virginia.edu/forums/opensem-forums/longitudinal-sem-and-latent-growth-curves