I am trying to do power analyses for a linear mixed model and a Kaplan-Meier survival analysis. All of my searches have only turned up the basic pwr commands, does anyone know what I should be using? cheers, Bridget
power analysis
2 messages · Bridget ONeill, ONKELINX, Thierry
2 days later
Dear Bridget, It is not easy to deduct a formula for the power for the more complicated models like linear mixed models. So what you can do in such a case is to use simulations. Simulate your data under know conditions, fit the model and see if you get a significant result. Repeat this a large number of times for each condition and you get an estimate of the power. HTH, Thierry ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 Thierry.Onkelinx at inbo.be www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey -----Oorspronkelijk bericht----- Van: r-sig-ecology-bounces at r-project.org [mailto:r-sig-ecology-bounces at r-project.org] Namens Bridget ONeill Verzonden: vrijdag 26 juni 2009 19:03 Aan: R-sig-ecology at r-project.org Onderwerp: [R-sig-eco] power analysis I am trying to do power analyses for a linear mixed model and a Kaplan-Meier survival analysis. All of my searches have only turned up the basic pwr commands, does anyone know what I should be using? cheers, Bridget _______________________________________________ R-sig-ecology mailing list R-sig-ecology at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document. The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document.