R Functions and User Interface

We will be implementing estimation for ordinal data soon.

We need to lock down an interface for the user to specify what is necessary for categorical estimation.

Issues I can think of right away include:

(1) Specifying data cast. That is, which columns are ordinal? If the observed data is an R dataframe, then this information is already included. Do we insist on dataframes in order to estimate ordinal columns? Or do we add another option somewhere?

Currently one of the least polished functions, and at the same time most visible to end users is the summary() function applied to the results of a model optimization.

We need suggestions about what this output should look like.

When specifying mxData() with both covariances and means, should the means vector be a row matrix or a column matrix?

1. Suppose a model has two free parameters.

2. You equate the two parameters by giving them the same name.

3. Now, you fix one of the parameters.

What should happen? One parameter is free and the other is fixed and they both are equated.

Currently OpenMx throws an error. Is there a more sensible thing to do?

OK. So that's a mouthful. This forum is primarily for the OpenMx developers. We will be talking with each other about the R functions that create the command line user interface for OpenMx. There are still a number of unresolved issues in how the user interface handles exceptions and conflicts, in how the function arguments are named, and in how output is structured.

Formerly, these questions were dealt with on a private mailing list. Now, we are making our developer discussions visible to the community.