I am hoping someone can help with the following:
I have been trying to use the ltm package in R to get person fit estimates using a 3PL model. The problem I have been having is that I start off with 4947 response patterns (dichotomous) but when I run
tpm()I end up with 4851 ability estimates and 4851 person fit estimates. I tried with another data set and ended up with a similar problem.
Here is the line of code I've used---
gr3is the dataset with 4947 lines of data containing zeroes and ones.
threePL <- tpm(gr3, na.action = NULL)
In addition, in order to run the 3PL model, I have to get rid of the person IDs, but I would like to retain the person IDs so that I can accurately map the ability and person fit estimates onto the right person.