st: In this particular case: should I prefer clustering or a random-effects model

[Andrea Bennett <mac.stata@gmail.com>]

Hi

I have student test scores for a generalized test. These tests were conducted at randomly selected high schools, in randomly selected classes with different levels of schooling (still all at high school level).

I want to measure individual performance after a exogenous treatment intervention in half of the sample. From what I understand, I could go with a standard regression and cluster on the class level, or I could use a random-effects model. Using fixed-effects dummies for each class is not appropriate since I only got 36 classes.

I've studied some articles and books but am still not quite sure if I should prefer one over the other (I tend to prefer a random-effects model). Any advice?

In addition, is it advisable to cluster on multiple levels (I have teachers participating with multiple classes, mostly at the same school but in two cases also at different schools). If so, what Stata command should I rely on since xtreg cannot do that?

Many thanks in advance,

Andrea
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