Hi,

I would like to compute confidence intervals for the ACE components in a univariate twins analysis.

Since I have categorical covariates in the model, the only way I could make the model work was by replacing the mxRun optimizer with mxTryHardOrdinal optimizer. However, according to the R documentation of the mxCI function, the mxCI could not run with other optimizers except for mxRun. Similarly, even though I ask for "intervals=TRUE" in the model, the lbound and ubound of the summary output are NAs.

I would like to ask:

1) is this really the problem?

2) if it is, how would you advice me to calculate the confidence intervals?

Thank you so much,

Lior

You should probably post the syntax you're trying to run. You can get confidence intervals with

`mxTryHardOrdinal()`

. You need to include the appropriate MxInterval object (which is created from`mxCI()`

) in your`mxModel()`

statement, and include argument`intervals=TRUE`

to`mxTryHardOrdinal()`

.Thank you.

In the meantime I decided to drop one of my covariates and now I can run the model with mxRun. This is the syntax, I hope it would help to understand the problem.

Thanks for posting the code. That helps a lot! Please see the documentation and especially the example for

`?mxCI`

. From thatBasically, you should create a confidence interval object with the mxCI function. Your call to this function should refer to free parameters, matrices, or algebras by name. You then put that CI object in the model before you run it.

Thank you! I understand my syntax mistake, and it works now