
From  Roger Harbord <rogerharbord@bigfoot.com> 
To  statalist@hsphsun2.harvard.edu, turnere@ohsu.edu 
Subject  st: Re: st: survival analysis: given median survival time ± 95% CI, how does one calculate SE, t, or exact p? 
Date  Sun, 22 Oct 2006 09:44:15 +0100 
Dear Stata users,
I am working with a report of data analyzed using survival analysis.
Specifically, the survival probabilities were calculated using the KaplanMeier method, and the estimated survival distributions were compared between groups using the logrank test.
For each group, they report the N, median survival time, and the 95% CI around the median. (The CIs were not calculated using a simple 1.96 x SE, because the upper and lower CI widths are different from one another.)
They also report exact P values, but only for where they get a value under .05.
Where the comparison between groups is nonsignificant, they just report "NS".
My goal is to find the exact P value (which I can get to if I can first get SE or t).
Would someone know how I can achieve this using Stata or some nottoodifficult formula?
Thank you.
Erick
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