[R] Kaplan Meier analysis: 95% CI wider in R than in SAS

[Frank Harrell]

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]]
>> >
>> >
>> > ______________________________________________
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>> > and provide commented, minimal, self-contained, reproducible code.
>> >
>>
>>
>> -----
>> Frank Harrell
>> Department of Biostatistics, Vanderbilt University
>> --
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>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
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>>
> 
> 	[[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.