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From |
"Stas Kolenikov" <skolenik@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Fitting Ordinal Item response Model using GLLAMM |

Date |
Tue, 28 Aug 2007 18:22:56 -0500 |

I think in -gllamm- slang you would need to look at -geq- option that describes equations explaining the random effects/latent variables. On 8/28/07, Swati Agiwal <agiwa001@umn.edu> wrote: > Hello All, > > I am using the GLLAMM program in Stata and wanted to know if anyone else is > using the same for fitting ordinal item response models. > > I am fitting a simple one parameter as well as a two parameter item > response model. I am interpreting the random effect as the latent variable. > However, I am facing difficulties in introducing other explanatory > variables into the existing item response models. I have looked through the > GLLAMM manual and there arent any similar examples. > > The current model I am fitting is : > > g(P(y{i}{j}<s)) = k{s} - b{i} - n{j}...Model(1) > > where g() is the ordinal probit function. y{i}{j} is the ordinal response > for person j on question/item i. k{s} are category thresholds, b{i} are > item biases and n{j} are the person specific random intercepts, which I > interpret as the latent variables. Model(1) is easy to fit in GLLAMM and is > well documented in Chapter 8 of the GLLAMM manual. > > To this i want to incorporate: > > n{j}= a*w1{j}+ c*w2{j} + q{j} > > That is, the latent variable n{j} is itself a function of person j specific > characteristics, say education w1{j} and income w2{j} and a new latent > variable q{j}. a and c are coefficients of the explanatory variables w1 and > w2. > > Thus the final model that i want to fit is : > > g(P(y{i}{j}<s)) = k{s} - b{i} - a*w1{j} - c*w2{j} - q{j}...Model(2) > > I am using all the items (87 of them) and all the persons (203 of them) > together is estimating this model. > If any does have an idea or suggestion as to how to fit Model(2) in GLLAMM > please do let me know. > > Thanks in advance, > Swati > > > > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > -- Stas Kolenikov, also found at http://stas.kolenikov.name Small print: Please do not reply to my Gmail address as I don't check it regularly. * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Fitting Ordinal Item response Model using GLLAMM***From:*Swati Agiwal <agiwa001@umn.edu>

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