Full_Name: Maria Rizzo Version: 2.10.1 (2009-12-14) OS: Windows XP SP3 Submission from: (NULL) (72.241.75.222)
platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 10.1 year 2009 month 12 day 14 svn rev 50720 language R version.string R version 2.10.1 (2009-12-14) scale returns incorrect values when center=FALSE and scale=TRUE. When center=FALSE, scale=TRUE, the "scale" used is not the square root of sample variance, the "scale" attribute is equal to sqrt(sum(x^2)/(n-1)). Example: x <- runif(10) n <- length(x) scaled <- scale(x, center=FALSE, scale=TRUE) scaled s.bad <- attr(scaled, "scale") s.bad #wrong sd(x) #correct #compute the sd as if data has already been centered #that is, compute the variance as sum(x^2)/(n-1) sqrt(sum(x^2)/(n-1)) ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
