For how to find the source code, see the help desk article in the October 2006 R news newsletter (http://cran.r-project.org/doc/Rnews/Rnews_2006-4.pdf) which was the predacessor of the R journal.
Have you looked at the variance of your jitters as well? that is what would make me more nervous (wide) or confident(narrow). On Fri, Mar 7, 2014 at 8:38 AM, David Parkhurst <parkh...@imap.iu.edu> wrote: > Thank you for your response. The first part of my question was meant to ask > "how do I actually find the source code?" I tried to find that, without > success. > > As for my comfort with a method that gives variable answers, I've > experimented by running 100 cases and take the average. When I've done that > on six different datasets from my real data with cor and method=kendall, the > mean tau from 100 jittering cases has been 5% to 10% lower than for the one > call without jittering. Given the many ties and zeroes in my data, I'm > inclined to think the mean value with jittering is likely to be a better > statistic. But I don't know. > > David > > > On 3/7/2014 10:25 AM, Greg Snow wrote: >> >> You could run the cor function on a small dataset where you know the >> values of tau-a and/or tau-b (either because you hand computed them, >> or found an example on the internet showing the difference), that >> would give some good evidence as to which is used. >> >> Or you could look at the source code, R is open source afterall. >> >> On the jittering question: are you comfortable with a method that >> would give a different answer every time you run it? >> >> On Thu, Mar 6, 2014 at 9:41 PM, David Parkhurst <parkh...@imap.iu.edu> >> wrote: >>> >>> How can I find out whether the cor function with method="Kendall" >>> computes >>> Kendall's tau-a or tau-b. I understand that tau-b deals better with >>> ties, >>> and I'm wanting to look for correlation in two variables that have lots >>> of >>> ties (especially lots of zeroes for one of them). The information >>> provided >>> by ?cor does not specify which is computed. >>> And a question: am I better off to jitter the variables before computing >>> tau, given the many ties? >>> >>> ______________________________________________ >>> 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. >> >> >> >> > -- Gregory (Greg) L. Snow Ph.D. 538...@gmail.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.
