I'm using the R package ltm to create a 2-parameter logistic regression.
The input matrix is sparse - many users have taken a small subset of the items in the item bank.
For some of my data sets i'm running into this error:
Error in if (any(ind <- pr == 0)) pr[ind] <- sqrt(.Machine$double.eps) : missing value where TRUE/FALSE needed
Not sure what the issue is. Doesn't repro on most of my data sets. Any thoughts?