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This is the community Wiki for the OpenMx project. If you got here from google you probably want the Home Page.

Full list of all pages on the wiki

Tips and FAQTs

Common Errors (and some less common ones)
Helper functions


The documentation
SEM Concepts
Simplified manual for beginners
OpenMx for mx 1.x users
OpenMx for Mplus users
OpenMx for Amos users
OpenMx for R users


Help with OpenMx functions and objects
The Main mx Functions
Operators and functions
Operator precedence
mxConstraint (constrain values within a model)
mxCompare(function to compare model fits)
mxCI (function to calculate confidence intervals)
mxEval (evaluate an algebra)
mxMatrix (matrix with labels, values, )
mxModel (container for parts of a model)
mxObjective (sets the likelihood target of a model)
mxRun (run a model)
omxgraphviz and making path diagrams
Writing a Demo Script


Projects under development


Can’t see what you want? Click here to create a new wiki page.

Registered users of forums can create pages here explaining SEM issues. Wikipedia maintains a page on Structural Equation Modeling, it is not, however, a how-to guide, no an in-depth examination, and we expect the SEM community will dive into very specific issues here.


saggen's picture

Problem with RAM notation specification...


I am not sure if I have come across a minor bug in the OpenMx RAM specification. For some reason I cannot free up an element of the S matrix when fitting a twin sub-model. I have tried several different syntax variations (i.e., using the label name and specifically freeing the S parameter element) to free up the parameter, but for some reason the specified covariance parameter element is not being estimated and included in the OpenMx output summary. The odd thing about this is that when checking the S matrix specification, the parameter is set to TRUE. Is this a known bug?



mhunter's picture

This is not the appropriate

This is not the appropriate spot for this question. Please make a forum post about it instead. I will be deleting this comment soon.

To address your question, that is definitely not the desired behavior. Could you provide a minimal code example that produces the bug? Or some part of the script that does this? It's difficult to track down where the problem is without some example to work with.

Another thing to check for is re-setting a parameter. If you set a parameter to free=TRUE in line 15 of your script and set it to free=FALSE in line 33, then it will silently be free=FALSE even though you set it to free=TRUE initially.

tbates's picture

make new page link?

good if this page had a link to create new pages...

seotools's picture

how to create a new page with

how to create a new page with link

rdr feed.txt 934 bytes
tbates's picture

did someone delete all the links out of this page?

seems not good that all the links are gone from the page?