And if you have SAS/STAT14.1 installed, then PROC GLIMMIX has an example (45.18 Weighted Multilevel Model for Survey Data) that covers a two level model, and an example of a three level model using the quadrature method to fit the data (45.19 Quadrature Method for Multilevel Model), that has students, classes and schools.  By combining the principles in these examples, I think you can get what you are after.   Steve Denham ... View more