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st: RE: ancova?


From   "FEIVESON, ALAN H. (AL) (JSC-SD) (NASA)" <alan.h.feiveson@nasa.gov>
To   "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Subject   st: RE: ancova?
Date   Tue, 18 Feb 2003 12:15:32 -0600

Daichi - Analysis of covariance won't work because that model assumes a
constant slope and different intercepts. More importantly, since subjects
are presumably a random sample from some population, you need a random
slopes model. You might try the Stata command -xtrchh- or the user-written
-glamm- package. Other options are to try multilevel modeling software such
as found in HLM, SAS or MLWIN.

Al Feiveson



-----Original Message-----
From: Daichi Nozaki [mailto:nozaki@p.u-tokyo.ac.jp]
Sent: Monday, February 17, 2003 2:47 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: ancova?


Dear all,

I recorded physiological responses for 3 different conditions
  from 10 subjects. In each condition, the data were obtained
several times with an associated variable.

Namely, the data look like this.
subject condition response assocvar
1 1 0.1 0.2
1 1 0.3 0.5
1 1 0.5 0.8
1 2 0.4 0.3
1 2 0.7 0.6
1 2 1.0 0.9
1 3 0.8 0.3
2 ..............
.................

I'd like to test the difference of physiological responses among
3 conditions after adjusting the data using the associated variable

Possibly, the slope of physiological response data to the associated
variable is different from subject to subject, but is independent
of the conditions within each subject.

I would appreciate if you would suggest how I can implement
this problem with Stata?

Thank you very much in advance.

Daichi Nozaki 

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