Just generate some data where the estimated survival probability is 0.9999 at a certain time. The log-log transformation blows up. Frank
Enrico Colosimo wrote > > What are the significant problems of the log-log transformations? > Any papers published about it? > Enrico. > > > 2012/4/14 Frank Harrell <f.harrell@> > >> I used log-log in my book too until Terry Therneau alerted me to the >> significant problems this creates. In the 2nd edition it will use log >> S(t). >> Frank >> >> Paul Miller wrote >> > >> > Hello Drs. Colosimo and Harrell, >> > >> > Thank you for your replies to my question. From Dr. Colosimo, I was >> able >> > to determine that the SAS results can be replicated by adding the >> > option conf.type="log-log" to my code as in : >> > >> > survobj <- survfit(survfrm, conf.type="log-log", data=Survival) >> > >> > Originally, it looked like the SAS results could be replicated using >> > conf.type="plain". Applying this option to my actual data revealed that >> > this was not the case, however. >> > >> >>From Dr. Harrell, I learned that using conf.type="log-log" may not be >> such >> a good idea. Interestingly though, I've seen at least one instance where >> experts in the R community use this option in their book. The book is >> about >> 10 years old. So maybe opinion about the use of this option has shifted >> since then. >> > >> > Thanks, >> > >> > Paul >> > >> > [[alternative HTML version deleted]] >> > >> > >> > ______________________________________________ >> > R-help@ mailing list >> > https://stat.ethz.ch/mailman/listinfo/r-help >> > PLEASE do read the posting guide >> > http://www.R-project.org/posting-guide.html >> > and provide commented, minimal, self-contained, reproducible code. >> > >> >> >> ----- >> Frank Harrell >> Department of Biostatistics, Vanderbilt University >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Kaplan-Meier-analysis-95-CI-wider-in-R-than-in-SAS-tp4554559p4557695.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> R-help@ mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@ mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ----- Frank Harrell Department of Biostatistics, Vanderbilt University -- View this message in context: http://r.789695.n4.nabble.com/Kaplan-Meier-analysis-95-CI-wider-in-R-than-in-SAS-tp4554559p4561432.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.