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Re: st: RE: : unpaired regression


From   "Winfield Scott Burhans" <wsb2@cornell.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: : unpaired regression
Date   Tue, 11 May 2004 20:17:36 -0400 (EDT)

John,
One more possibility, last one from me.  Assuming your interest is in the
variance between batches, use either xtreg or gllamm.

Line up the results as Scott suggested, then do either xtreg or gllamm.
Rather than being interested in the significance of the coefficient on the
predictor assay, the outcome of interest would be the significance of
either  sigma_u (xtreg) or the level two term "batch" in gllamm. In
gllamm, you could use -gllapred-  with the ustd option to identify
specific outlier batches

xtreg assay1 assay2, i(batch)

or

gllamm  assay1 assay2, i(batch) adapt
gllamm, allc

Buzz Burhans


>> I have two measures of batch performance on which I'd like to
>> perform a
>> regression.  The measurements are taken on separate samples
>> from the batch,
>> and typically look something like:
>>             Assay1 Assay2
>> Btch1    5400
>> Btch1    5320
>> Btch1    5670
>> Btch1                0.900
>> Btch1                0.905
>> Btch1                0.898
>> Btch2    8600
>> Btch2    7840
>> Btch2    7550
>> Btch2                0.962
>> Btch2                0.955
>> Btch2                0.943
>> ...etc (on for multiple batches which show correlated
>> measures for the two
>> assays)
>> -collapse- ing them to batch averages and then performing the
>> regression is
>> one approach, but it doesn't take variance of the measures
>> themselves into
>> account in the regression.  Is there a system for performing
>> this type of
>> analysis?
>>
>
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