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

Jeff r at jp.pair.com
Wed Mar 28 08:22:05 CEST 2012

   I'm new to R and this list.
   I'm using the LTM package for the first time to estimate Rasch and grm
   I've  searched  the web and the list archives and have found an almost
   identical question to my current one, but I haven't found an answer. I'm
   going to repeat the question that someone else asked two years ago (March
   20, 2010) to see if anyone can provide an answer to this issue.
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
rows (individuals) in my data matrix (hopefully in the same order
my data matrix) such that the length of the theta vector = the
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
with each response pattern in my data along with the number of
each response pattern occurs.  Any ideas on how to get the
vector of theta estimates? Thanks,

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