Ahamarshan jn wrote: > I did a correlation for the values > > - EX4577 EX4599 EX4566 EX4522 > WL917 2.53528 0.79077 0.21499 -0.01084 > WP429S -0.192723715 > WP819 -1.016997552 > WP977 1.378674 -0.07071 0.625089 0.4728363 > WI205S -0.24443 -1.789526 0.648923 -0.775867 > > > by using > round(cor(t(person.data),use="pairwise.complete.obs")) > > i got the result as > > - WL917 WP429S WP819 WP977 WI205S > WL917 1 NA NA 0.344 -0.11424 > WP429S NA NA NA NA NA > WP819 NA NA NA NA NA > WP977 0.34461 NA NA 1 .23294 > WI205S -0.11424NA NA 0.23294 1 > > i notice that > for correlation between WP429S x wp429S the value is > given as NA where as it should be 1 > same is the case with WP819 x WP819 > > Can someone please help me reason out why this is > happening? and any corrective measure that I need to > take so that I can get the true value of 1 for them. > > Thank you > - ash# >
Hi, Ash, It's difficult to tell with the data you provided (maybe just poor email formatting), but it looks like both WP429S and WP819 have only one value. You cannot obtain a correlation with only one value (see any intro stats book for the definition or correlation or just Google it). Try: x <- rnorm(1) y <- rnorm(1) cor(x, y) cor(matrix(x, 1, 1)) This is because x and y have zero variance. Forcing the "NA" to "1" as a "corrective measure" would be incorrect and misleading. HTH, --sundar ______________________________________________ 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
