IRT EAP scores and missing data PreviousNext
Mplus Discussion > Confirmatory Factor Analysis >
 Matthew White posted on Sunday, April 10, 2016 - 8:56 pm
Hi Drs. Muthen,

When estimating the value of theta (ability) from an IRT model using the Expected A Posteriori method, how does Mplus handle records with missing values for 1 or more items? Does it simply use the remaining non-missing items? Is there a proportion for missing items above which it does not make sense to calculate theta (e.g., 50%)? In case it is important, I am using a 2-parameter logistic IRT model with binary items.

 Bengt O. Muthen posted on Monday, April 11, 2016 - 6:34 pm
Q1. The parameter estimation uses all available data with ML assuming MAR. The ability (factor score) estimation uses the subject's non-missing items.

Q2. That's difficult to say but you do get a SE for the factor score estimate for the person so that can tell you about lack of precision.
 Weizi Wang posted on Monday, June 12, 2017 - 4:04 am
I am wondering how to estimate the theta (ability) using Mplus. Is it the factor score output by the program the estimate of the theta? If so, I am wondering how to output all the factor scores since they are not outputted completely by default.
 Bengt O. Muthen posted on Monday, June 12, 2017 - 5:48 pm
Yes, the factor scores are the theta estimates. Use the Savedata command and the option Save=fscores.
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