Hello, I want to compute the so-called IRT Item Information Function for individual items as well as the latent variable using Stata. Several methods are available for IRT analysis, like clogit, gllamm or raschtest, but so far I could not find any syntax to draw the Information Function using anyone of these methods. So, any help or example is much appreciated.
Hi Eric,
I've written ados for this.
ado at -> https://dl.dropboxusercontent.com/u/458793/ado/i/icc_2pl.ado
help file at -> https://dl.dropboxusercontent.com/u/458793/ado/i/icc_2pl.sthlp
No warranty express or implied. But I think they are right. Let me know if you have problems or questions. Email in the help file. Copy these to your ado/personal/i folder or wherever Stata will look for ados.
Rich
Dear Richard,
Many thanks, this is really helpful.
I will write you with my questions.
Eric
The other answer to this question, Eric, is to switch to R, which has a more active community of users in general, and also in areas related to psychometrics. After about 15 years of using Stata, and having written -- literally -- 1,000+ custom ados to streamline my data analysis, I'm making the switch.
Hm, I see, I have nothing against R and I appreciate your view, but myself I am much more comfortable with Stata. Thank you anyway for your kind help.
Dear Richard,
This morning I did not see the options test info in the help file of icc_2pl.
Now I did, and the great news is that thanks to icc_2pl, I am also able to create the item information plots and the test information plot.
So, I really have to thank you again for your ado file, and I think you should share it with the Stata community too. It is a great time saver to have this.
Best regards,
Eric
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