Frank, would you feel comfortable giving us the reference to the NEJM article with the 'missing vs <' error ? I'm sure that things like this happen fairly often, and I'd like to use this example in teaching
thanks, david freedman Frank E Harrell Jr wrote: > > Dieter Menne wrote: >> >> >> P.Dalgaard wrote: >>> >>>> IF TYPE='TRUCK' and count=12 THEN VEHICLES=TRUCK+((CAR+BIKE)/2.2); >>> vehicles <- ifelse(TYPE=='TRUCK' & count=12, TRUCK+((CAR+BIKE)/2.2), NA) >>> >>> >> >> Read both versions to an audience, and you will have to admit that this >> is >> one of the cases where SAS is superior. > > Here's a case where SAS is clearly not superior: > > IF type='TRUCK' AND count<12 THEN vehicles=truck+(car+bike)/2.2; > > If count is missing, the statement is considered TRUE and the THEN is > executed. This is because SAS considers a missing as less than any > number. This resulted in a significant error, never corrected, in a > widely cited New England Journal of Medicine paper. > > Frank > >> >> Dieter >> >> > > > -- > Frank E Harrell Jr Professor and Chair School of Medicine > Department of Biostatistics Vanderbilt University > > ______________________________________________ > 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. > > -- View this message in context: http://www.nabble.com/SAS-like-method-of-recoding-variables--tp24152845p24165879.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.
