Re: [amelia] Error Messages

On Thu, 30 Aug 2007, Glenys Lafrance wrote: First off, you might not need to declare variables as ordinal. Generally you only need to do this for variables that are going to be used in an analysis model that requires ordinality (like a Logit, Poisson, Ordered Probit, and the like), and even then, only for the Dependent variable. (Remember, Nominal variables are another matter, and always need to be declared.) It might seem unintuitive to allow imputations to have a space that is not the same as the original data, but if you are rounding the imputations you are losing information. An imputation of .51 on a dichotomous variable tells you that in that imputed dataset, the imputation was nearly as likely to be a 1 as a 0. Very few models require right hand side variables to be ordinal, although it may make graphs look more intuitive. Anyway, not to deny your question, it seems like something might be wrong in the way you are setting either the "ords" or "idvars" arguments. We have a list of checks to try to catch common errors (and I make most of them myself, commonly) but there are always interesting ways to define these arguments in ways that are logically incompatible, that we've yet to think of. Just check over them one more time. In the latest version of Amelia you can set them either by using the a vector of the column number, or a vector of variable names. The latter is less likely to trip you up. This is all assuming you are using R code of your own, and not using the AmeliaView interface, which ought not to allow you to do anything you can't do. Let me know if you don't find your error, or are certain you've set things out right. We try to write in useful error messages, but whatever event occured did not trip one. There is not something built in to do this, although declaring variables as Ordinal will make certain that the imputations take integer values (if the original data is integer). But it does not do this by rounding. regards, James Honaker - Amelia mailing list served by Harvard-MIT Data Center [Un]Subscribe/View Archive: http://lists.gking.harvard.edu/?info=amelia