# RE: st: equivalence limit-thanks

 From Ricardo Ovaldia To statalist@hsphsun2.harvard.edu Subject RE: st: equivalence limit-thanks Date Sun, 16 Aug 2009 09:47:47 -0700 (PDT)

```Thank you very much Joseph. That is the information that I needed.

Ricardo
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK

--- On Sun, 8/16/09, Joseph Coveney <jcoveney@bigplanet.com> wrote:

> From: Joseph Coveney <jcoveney@bigplanet.com>
> Subject: RE: st: equivalence limit
> To: statalist@hsphsun2.harvard.edu
> Date: Sunday, August 16, 2009, 10:49 AM
> Ricardo Ovaldia wrote:
>
> I am still trying to figure how to do an equivalence test
> in Stata.
> All I have is a 2x2 table (Treatment x outcome). I can use
> -cs- or -rdci-
> to get the CI, but how do I compute the equivalence limit
> assuming delta=25%,
> for example?
>
> Also, can -pkequiv- be trick into doing this analysis?
>
> --------------------------------------------------------------------------------
>
> If your delta is 25% for a risk difference (difference in
> proportions), then you
> can reject the null hypothesis of nonequivalence in favor
> of the alternative
> hypothesis of therapeutic equivalence if the confidence
> interval (CI) from -cs-
> (Wald) or -rdci- (various other methods) lies between -0.25
> and +0.25.
>
> For equivalence (as opposed to "noninferiority"), a 90% CI
> is conventionally
> used.  This corresponds to a two, one-sided test
> (TOST) method with alpha =
> 0.05.
>
> So, set -level- at 90% for -cs- or -rdci- (whichever
> command you choose), and if
> the displayed CI is between the limits that you set for
> equivalence (e.g., -0.25
> to +0.25, in your example), then you can declare
> bioequivalence.
>
> Joseph Coveney
>
>
>
> *
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>

*
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```