Tomas, What I would do is calculate the median and a confidence interval in the transformed space. Since the log transformation is a monotone transformation it will preserve the order of the values. So the median stays the median, the 2.5% quantile stays the 2.5% quantile and so on. But be aware that while in the transformed space the median equals the mean (= the prediction), this will not hold when you backtransform the values to the original scale.
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 [EMAIL PROTECTED] 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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Namens Tomas Easdale Verzonden: donderdag 24 april 2008 5:24 Aan: r-sig-ecology@r-project.org Onderwerp: [R-sig-eco] log link versus log response 2 Thanks Scott, That response is very useful and it all makes sense now as LOG transforming the response works better for heterocedastic data. But your response also brings me to a second question that has been circulating around. What can/should I do if I want to use my regression to predict responses in the original scale. Exponentiate the errors? That doesn't seem much feasible, is it? Cheers Tomas [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
