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st: -stpower- for categorical vars?
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Subject
st: -stpower- for categorical vars?
Date
Fri, 15 Nov 2013 14:57:22 +0800
Dear Statalist,
I am attempting to calculate the power of some survival analyses, but
have more than just a binary variable of interest- that is, I have
low, medium and high doses.
Let's say I have a study with n=15 for each exposure:
stpower cox, n(45) hr // assuming a binary
Obviously if I have low-medium-high, the power < 0.6424, but is there
any way to calculate that, or should I just use the N from the two
smaller categories?
stpower cox, n(30) hr
There is discussion in the Stata 13 -st- manual about continuous
covars of interest (Example 2, pg 281) but not categoricals. Any
thoughts?
cheers-
Andrew Lover
___________________________________________________
Epidemiologist
Centre for Infectious Disease Epidemiology Research (CIDER)
Saw Swee Hock School of Public Health
National University of Singapore
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