Hi, Peter's suggestion is more general, but for just the weighted mean, there is a built in function you can use (I do not know of any basic weighted standard deviation or variance functions).
dat <- data.frame(age = 1:5, no = c(21, 31, 9, 12, 6)) weighted.mean(x = dat$age, w = dat$no) Best regards, Josh On Mon, Sep 27, 2010 at 9:34 AM, Jonas Josefsson <jo...@runtimerecords.net> wrote: > I have a two-column table as follows where age is in the 1st column and the > number of individuals is in the 2nd. > > age;no > 1;21 > 2;31 > 3;9 > 4;12 > 5;6 > > > Can I use mean() and sd() to calculate the mean and standard deviation from > this or do I have to manually multiplicate 21*1+31*2 etc. / N? > > ______________________________________________ > 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. > -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.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.
