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

By *mkeller*

Created *05/28/2010 - 01:30*

Fri, 05/28/2010 - 01:30 — mkeller [1]

Hi all,

I appreciate the speedy help that comes with posting on the forums here.

I have two separate problems so thought I'd post them both here:

PROBLEM 1: I'm trying to fit a model using var/cov matrices rather than raw data, as suggested by Steve in an earlier post (in order to get rough ideas of good start values for later FIML fitting). However, I get the following error message (pasted before it is the last bit of the script so you can see how I set up the Objective functions

+ ),

+ mxModel("DZOS",

+ mxData( observed=dzmfcov, type="cov" ,means=dzmfmeans , numObs=nrow(dzosData)),

+ # mxFIMLObjective( covariance="NTF.expCovDZOS", means="NTF.expMeanMF", dimnames=selVars )

+ mxMLObjective( covariance="NTF.expCovDZF", means="NTF.expMeanF", dimnames=selVars )

+

+ ),

+ mxAlgebra( expression=MZM.objective + MZF.objective + DZM.objective + DZF.objective + DZOS.objective, name="neg2sumLL" ),

+ mxAlgebraObjective("neg2sumLL")

+ )

> system.time(multiHetNTFFit <- mxRun(multiHetNTFModel))

Running multiHetNTF

Error in mxRun(multiHetNTFModel) :

Could not initialize objective function MxMLObjective. Error: No error code reported.

PROBLEM 2: Not being able to make headway on the above error, I went back to the FIML approach, but I'm getting non-positive def matrices:

> system.time(multiHetNTFFit <- mxRun(multiHetNTFModel))

Running multiHetNTF

Error: The job for model 'multiHetNTF' exited abnormally with the error message: Expected covariance matrix is not positive-definite in row 230.

I've looked over the expected cov matrices and cannot see where the problem is. I've tried changing start values but to no avail. Is the "row 230" a helpful hint at all? If so, how does one interpret this?

THANKS AGAIN!

matt

**Links:**

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

[2] http://openmx.psyc.virginia.edu/thread/529

[3] http://openmx.psyc.virginia.edu/thread/430

[4] http://openmx.psyc.virginia.edu/forums/openmx-help/openmx-general-help