Have a look at ?IQR "Note that this function computes the quartiles using the quantile function rather than following Tukey's recommendations, i.e., IQR(x) = quantile(x,3/4) - quantile(x,1/4)."
It looks like boxplot() gives the results you expect. tt <- boxplot(x) tt --- On Tue, 9/8/09, Chunhao Tu <tu_chun...@yahoo.com> wrote: > From: Chunhao Tu <tu_chun...@yahoo.com> > Subject: [R] strange results in summary and IQR functions > To: r-help@r-project.org > Received: Tuesday, September 8, 2009, 11:09 AM > > Dear R users, > Something is strange in summary and IQR. Suppose, I have a > data set and I > would like to find the Q1, Q2, Q3 and IQR. > > x<-c(2,4,11,12,13,15,31,31,37,47) > > summary(x) > Min. 1st Qu. Median > Mean 3rd Qu. Max. > 2.00 11.25 14.00 20.30 31.00 47.00 > > > IQR(x) > [1] 19.75 > However, I test the same data set in SAS "proc univariate", > and SAS shows > that Q1=11, Q2=14 and Q3=31. I think most of us agree that > Q1 is 11 not > 11.25. > > Could someone please explain to me why R shows Q1=11.25 not > 11? > > Many Thanks > Tu > > > -- > View this message in context: > http://www.nabble.com/strange-results-in-summary-and-IQR-functions-tp25348079p25348079.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. > __________________________________________________________________ Looking for the perfect gift? Give the gift of Flickr! http://www.flickr.com/gift/ ______________________________________________ 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.