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

By *cvanhulle*

Created *11/17/2011 - 18:42*

Thu, 11/17/2011 - 18:42 — cvanhulle [1]

I'm trying to add covariates to an ordinal ACE model. I want to include gender effects on the threshold, but I keep getting the following error: Error: In model 'univACEOrd' the thresholds in column 'clu2T1' of matrix/algebra 'MZ.expThreMZ2' are not in ascending order. The current order is: 'NA' and ascending order is: . Only the first 1 value(s) of this column are inspected.

I have no idea what that error means.

>

I'm letting the thresholds differ by zygosity. My script for MZ twins is

mxModel("MZ",

mxMatrix( type="Full", nrow=1, ncol=nv, free=TRUE, values=1.13, label="threMZ", name="T" ),

mxAlgebra( expression= cbind(T,T), dimnames=list('th1',selVars), name="expThreMZ1" ),

mxMatrix(type="Full", nrow=1, ncol=2, free=F, label=c("data.gender1","data.gender2"), name="MZDefVars"),

mxAlgebra(expression=expThreMZ1 + ACE.beta %*% MZDefVars, name="expThreMZ2"),

mxData( observed=mzData, type="raw" ),

mxFIMLObjective( covariance="ACE.expCovMZ", means="ACE.expMean", dimnames=selVars, thresholds="expThreMZ2" )

),

Neither beta from the ACE part of the model nor expThreMZ1 is null. Any advice would be greatly appreciated.

Thanks.

**Links:**

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

[2] http://openmx.psyc.virginia.edu/thread/1186

[3] http://openmx.psyc.virginia.edu/thread/1109

[4] http://openmx.psyc.virginia.edu/forums/opensem-forums/behavioral-genetics-models