I am trying to estimate school effects on student scores. I ran a model with student effects as a random effect and school effects as fixed effects as follows:
xtreg studentscore lagstudentscore limitedEng poor `gradeyeardum' `schoolyeardum', re
where student score is regressed on lag of student score, student's language proficiency and poverty status, and a set of grade-year dummy variables and a set of school-year dummy variables. The coefficients on the school-year dummy variables are the key fixed effects of interest.
I want to estimate an equivalent model using
xtmixed. I ran the code below but the MLE doesn't seem to converge - I got the "not concave" message for several iterations. Here's the code I ran:
xtmixed studentscore lagstudentscore limitedEng poor `gradeyeardum' schoolyeardum', || schnamyearid : || studentid:
I am not sure if I should estimate both the individual level and school level standard deviations for the variance component. I am interested in the school level variation, so perhaps the following model makes more sense?
xtmixed studentscore lagstudentscore limitedEng poor `gradeyeardum' schoolyeardum', || schnamyearid :