These are discussed in the methods and formulas section of the manual
entry on -sts-. Anyhow, you can let Stata do the computations by typing
-sts list-.
Hope this helps,
Maarten
--- Hugh Robinson <[email protected]> wrote:
> Can anyone tell me how to calculate the variance of a Kaplan-Meier
> survival estimate derived from the Nelson-Aalen hazard function?
>
> For instance, Stata provides a Standard Error of 0.08 for a
> cumulative
> NA hazard of 0.22. The hazard function is easily converted to the
> Kaplan-Meier equivalent as S= exp(-H). In this case the equivalent
> Kaplan-Meier S = exp(-0.22)=0.80. However I am unclear as how to
> calculate the equivalent variance. According to Cleves et al, Stata
> uses the Greenwood method to calculate standard error for
> Kaplan-Meier
> estimates. A second source suggests that variance should be the same
> for both and calculated as the sum of (# of events/# at risk) for
> each
> time step.
>
>
> Thanks.
> HR
>
>
> Hugh S Robinson Ph.D.
> Postdoctoral Researcher
> Wildlife Biology Program
> College of Forestry and Conservation
> University of Montana
> Missoula, MT 59802
> (406) 243-4128
>
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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*
* For searches and help try:
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* http://www.ats.ucla.edu/stat/stata/
