No subject

I've got a table of 1 row per observation.  

16 questions * n subjects * 4 classrooms (2 teachers * 2 conditions)

I'd like to run some simple regressions that look something like this:

  lm(length ~ elapsed)

I'd like to do the regressions several times, split out by
questionkey, student, class.  What I've been doing is using a series
of which's to create new data sets (e.g. class1, class2, class3,
class4) and running the regressions (or whatever) against each of
those new data sets.  It seems that there should be better a way to do
this.

Jay Pfaffman                           pfaffman at relaxpc.com
+1-415-821-7507 (H)                    +1-415-810-2238 (M)

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