Hi R users!

I am trying to learn some multilevel analysis, but unfortunately i am now very confused. The reason: http://www.ats.ucla.edu/stat/hlm/seminars/hlm_mlm/mlm_hlm_seminar.htm
http://www.ats.ucla.edu/stat/sas/seminars/sas_mlm/mlm_sas_seminar.htm

and
MlmSoftRev. pdf from mlmRev package. 

>From what i see, the first two links seem to declare the level one variable as a random part (i don't know sas synthax, but i think i am right ) while Mr. Bates' pdf  says that a grouping variable is the random part of the model, though both models, use roughly the same type of information, some characteristic of the school, along with individual characteristics in explaining individual achivement. 

Am i mistaken somehow? If not, could they both be valid models (i presume) but each showing something else, in terms of connections between this variables?

Thank you and sorry for taking up your time.

       
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