OpenMx Developer Forums

At developers meeting on 10/21 we discussed the following:

• The group reviewed the state of the multi-level modeling effort.

At developers meeting on 10/14 we discussed the following:

• Dan Hackett is investigating some issues with the standard errors in PPML. The standard errors do not match OpenMx for some larger container models. Dan is investigating this further. We believe this is because the standard errors are unstable. Thus even the same algorithms are capable of producing different standard errors because the estimates are moving around in space so much.

At developers meeting on 10/7 we discussed the following:

• The group is close to getting OpenMx thread-level parallelism working for calculating the hessian. Michael Spiegel, Tim Brick and Ross are working on addressing the final loose ends and testing the implementation to ensure it calculating the hessian values correctly.
• We discussed possible funding opportunities at the Census Board for OpenMx. OpenMx would serve as an improved data management and collaborative analysis environment for census data analysis.

At developers meeting on 9/16 we discussed the following:

• The group discussed the updates made to the OpenMx documentation. Specifically, the following was discussed:
  • The use of the 'you' in the documentation. While using 'you' can be seen as informal, the group decided it was appropriate for the user guide.
  • Balancing the font size of the html documentation with what font size will fit on the page in the pdf documentation.
  • Possible coloring issues for color blind readers.

Hey, all.

I put this together for someone and thought I'd share it. It's a quick helper function for building an MxAlgebra object that takes a string instead of an expression as the first argument.


stringToMxAlgebra <- function(algString, name=NA, dimnames=NA) {
eval(substitute(mxAlgebra(tExp, name=name, dimnames=dimnames), list(tExp = parse(text=algString)[[1]])))
}


At developers meeting on 9/16 we discussed the following:

• The group updated the status of the effort to parallelize the FIML Objective function. Several issues exist:
  • RMPI uses point-to-point communication when it should not. As a result it is not as efficient as it should be.

At developers meeting on 9/9 we discussed the following:

• Timo implemented a change to the determinant calculation in omxFIMLObjective.c and omxMLObjective.c. Now we take logs of each element rather than doing multiplies and taking log of the result. This process is significantly more stable.
• Several bugs related to the joint continuous/ordinal FIML optimization. We will be updating the test suite to include test cases to ensure that an error is not thrown for the patched issues.

At developers meeting on 9/2 we discussed the following:

• There is a bug in the implementation of Joint/Ordinal in OpenMx 1.1. It seems to be triggered by including an additional variable (or column) in the data that is not included in the analysis, resulting in the multiplication of non-conformable arrays. The team is continuing to look into this issue.

Thanks for implementing the analysis of ordinal data in OpenMx 1.1. After running the code, it seems that there are some errors in the example.

Original S matrix:
mxMatrix(
type="Symm",
nrow=4,
ncol=4,
values=c(1,0,0,0,0,0,0,
0,1,0,0,0,0,0,
0,0,1,0,0,0,0,
0,0,0,1,0,0,0,
0,0,0,0,1,0,0,
0,0,0,0,0,1,0,
0,0,0,0,0,0,1),
free=c(T, F, F, F,