John Moran wrote (excerpted):
There are numerous entries in "search" for interactions in Stata, but
somewhat surprisingly, none (including "findit") for the "Gail-Simon" test
for qualitative interactions (M. Gail and R. Simon. Testing for Qualitative
Interactions between Treatment Effects and Patient Subsets. Biometrics 41
(2):361-372, 1985).
This test has been used frequently, albeit with some degree of controversy,
in the medical trial literature and has also been featured in the excellent
text: A Dmitrienko, Geert Molenberghs, C. Chuang-Stein, and W. W. Offen.
Analysis of clinical trials using SAS: A practical guide, Cary, NC:SAS
Institute Inc., 2005.
Not having access to SAS (!!), I wonder if anyone has coded this test in
Stata?
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