Adjusting for age in longitudinal setting

No replies
Ahmed's picture
Joined: 04/02/2013

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!