[R] Getting a complete vector of Theta estimates from Package LTM

James L. Lewis j.luria at ucla.edu
Sat Mar 20 05:40:28 CET 2010


I am using package LTM to estimate a Rasch model:

irtestimates <- rasch(binRasch)

I want to get a single vector containing theta estimates for all the  
rows (individuals) in my data matrix (hopefully in the same order as  
my data matrix) such that the length of the theta vector = the number  
of rows (participants) in my data matrix. I am using:

theta.est <- factor.scores(irtestimates,method="EAP")

The problem is that this does not return a vector of ALL the theta  
estimates, rather it gives me a summary of theta estimates associated  
with each response pattern in my data along with the number of times  
each response pattern occurs.  Any ideas on how to get the complete  
vector of theta estimates? Thanks,

Jimmy



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