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st: strange confidence intervals in survival analyses
Dear all -
I am trying to calculate mortality rates using Stata 7.0, but am having a problem with confidence intervals. In my survey data set, I have a dichotomous outcome variable representing death, and a second variable representing person-time. I have been using "stset" to convert the data into survival-time, and "stptime" to calculate mortality rates. This all seems to work very well except when I add p-weights. The confidence intervals I get for the weighted estimates seem, well, improbable: e.g. an estimate of 8.2 is reported to have a 95% CI of 3.0, 3.0. This problem is especially common in analyses with low numbers of deaths.
Has anyone else encountered this problem? Is the problem mine or Stata's?
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