Breslow & Day has a nice three page discussion in volume 2 of their
"Statistical Methods in Cancer Research". See pages 285-7. Most of the
gain in power comes from the decrease in degrees of freedom and only
if the trend is approximately linear. Alternatives that are quadratic
are not well detected.
Failing that, the usual answer is simulate it.
--
David Winsemius
On Mar 2, 2009, at 6:12 PM, Bill Hyman wrote:
>
> Hi all,
>
> Is there any way we can to power analysis for prop trend test? Many
> thanks!
>
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