st: Question about felsdvregdm/felsdvreg

["O'Brien, Rachel H" <rhobrien@stanford.edu>]

Hi.  I am trying to use felsdvregdm to estimate teacher fixed effects and have run into an issue.  After I ran the program, I discovered that there was a mass of teachers with a FE estimate of 0.  Upon further investigation, I determined that all of these teachers have group==.  I am confused because I don't know what it means for group to be missing (although my guess is that these teachers' students never appear in other classes).  More importantly, I am running a one-level model, so my understanding is that group should be irrelevant, and I don't know why it would cause all of the estimates to be 0.  

In case it matters, in the model I am centering the estimates by the teacher's grade.  In my first run of the program, I inadvertently omitted one grade dummy.  I tried to fix this in a second run, but then I got the error message:

             decompreg():  3498  Firm effects are collinear with explanatory variables - cannot proceed
                 <istmt>:     -  function returned error

This confused me because the help file for the command indicates that you should include all indicators (there is no constant).  Now I am running the program without the dummies explicitly included which should force the program to include them for me.

Any help would be appreciated!

Rachel 

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