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RE: st: equivalence tests


From   "Steichen, Thomas J." <SteichT@rjrt.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: equivalence tests
Date   Tue, 10 Jul 2007 13:29:32 -0400

Joseph Coveney wrote:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Ronan Conroy wrote:

Has anyone cooked up a tost (two one-sided tests) ado?

--------------------------------------------------------------------------------

Isn't it something like that below?  (Also, "test1:" and "test2:" reported
by -equim- are the TOST.)

Joseph Coveney

clear
set more off
sysuse auto
ttest price, by(foreign) level(90)
local delta = 0.2 * r(mu_1) // Domestic is "reference group"
* Option 1:  By inspection, declare therapeutic equivalence if
* 90% CI is contained within the interval -delta to +delta
display in smcl as result `delta'
* Option 2:  Schuirmann's Two One-sided Tests (TOST);
* reject at alpha = 10% (5%, one-sided)
* (Note: TOST is operationally equivalent to Option 1 above)
local difference = r(mu_1) - r(mu_2) // mu_reference - mu_test
display in smcl as result 2 * ttail(r(df_t), (`delta'-`difference')/r(se))
display in smcl as result 2 * ttail(r(df_t), (`delta' + `difference')/r(se))
exit
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Yes, it is very much like that (even identically so), however, as noted 
by the author of -equim- in a post today, -equim- gives wrong answers 
when certain relatively common conditions occur, so cannot always be trusted.

Tom

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