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From | Steve Samuels <sjsamuels@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: confidence intervals of predicted risk after stcox |
Date | Fri, 26 Oct 2012 17:15:04 -0400 |
Mario, when I run your code, and sum the new variables, I get: Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- lb15 | 48 .2283326 .2110915 .0112244 .6184661 risk15 | 48 .4723272 .343838 .0406233 .9987398 ub15 | 48 .7089512 .3057171 .1413257 1 I see nothing strange about them. What is it that does not make sense to you? Steve On Oct 26, 2012, at 6:45 AM, petretta@unina.it wrote: Hi all, I use Stata/IC 12.1 for Windows (32-bit). I run a Cox model to calculate for each patient the predicted probability of event at 15 months, using predict xb, predict basesurv and adjiusting the baseline risk webuse cancer, clear gen age40=age-40 stcox age40 i.drug predict xb, xb predict basesurv, basesurv sum basesurv if _t<16 scalar base15 = r(min) gen risk15 = 1 - base15^exp(xb) I ask if it is possible to have also the 95% confidence intervals of these estimate. I try: predict se_xb, stdp gen lb = xb - invnormal(0.975)*se_xb gen ub = xb + invnormal(0.975)*se_xb gen lb15 = 1 - base15^exp(lb) gen ub15 = 1 - base15^exp(ub) but the results seems do not have sense. Thanks for your consideration. Mario Petretta Dpt. of Internal Medicine, Cardiology and Heart Surgery Naples University Federico II -Italy * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/