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From |
Maarten buis <maartenbuis@yahoo.co.uk> |

To |
stata list <statalist@hsphsun2.harvard.edu> |

Subject |
Re: st: SE's on survival estimates from parametric models |

Date |
Mon, 27 Apr 2009 09:16:42 +0000 (GMT) |

--- On Sat, 25/4/09, Mark Hebblewhite wrote: > Thanks for your suggestion, it worked! But it produced, as > expected with the predict command, a prediction of the > mean survival rate and SE for each individual row/animal > in my dataset. > > To obtain one estimate of survival for say, the entire > dataset, would it then be appropriate to just use summary > statistics to calculate group-level means and SE's? Below is an example of how to compute the hazards, se, and confidence intervals at t=15 for someone of average age, but still differentiated by drug. If you want one number, then also replace the variable drug with one representative value e.g. the mode. *------------- begin example ------------------- sysuse cancer, clear stset studytime, failure(died) xi: streg i.drug age, dist(weibull) preserve local t = 15 local p "exp([ln_p]_b[_cons])" local h0 "`p' *`t' ^(`p' -1)" sum age if e(sample), meanonly replace age = r(mean) bys drug : keep if _n == 1 predictnl hazard = `h0' * exp(xb()), ci(lb ub) se(se) list drug hazard se lb ub, clean noobs restore *-------------- end example -------------------- ----------------------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://home.fsw.vu.nl/m.buis/ ----------------------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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