Hi, You can try with cor.test(rank(y[1]),rank(y[2]))
On 5/29/07, Raymond Wan <[EMAIL PROTECTED]> wrote: > > Hi all, > > I am trying to figure out the formula used by R's Spearman rho (using > cor(method="spearman")) because I can't seem to get the same value as by > calculating "by hand". Perhaps I'm using "cor" wrong, but I don't know > where. Basically, I am running these commands: > > > y=read.table(file="tmp",header=TRUE,sep="\t") > > y > IQ Hours > 1 106 7 > 2 86 0 > 3 97 20 > 4 113 12 > 5 120 12 > 6 110 17 > > cor(y[1],y[2],method="spearman") > Hours > IQ 0.2319084 > > [it's an abbreviated example of one I took from Wikipedia]. I > calculated by hand (apologies if the table looks strange when pasted > into e-mail): > > IQ Hours rank(IQ) rank(hours) diff diff^2 > 1 106 7 3 2 1 1 > 2 86 0 1 1 0 0 > 3 97 20 2 6 -4 16 > 4 113 12 5 3.5 1.5 2.25 > 5 120 12 6 3.5 2.5 6.25 > 6 110 17 4 5 -1 1 > 26.5 > > rho= 0.242857 > > where rho = (1 - ((6 * 26.5) / 6 * (6^2 - 1))). I kept modifying the > table and realized that the difference in result comes from ties. i.e., > if I remove the tie in rows 4 and 5, I get the same result from both cor > and calculating by hand. Perhaps I'm handling ties wrong...does anyone > know how R does it or perhaps I need to change how I'm using it? > > Thank you! > > Ray > > ______________________________________________ > R-help@stat.math.ethz.ch 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. > -- "The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane." Nikola Tesla http://www.macgrass.com ______________________________________________ R-help@stat.math.ethz.ch 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.