On 2010-09-27 15:20, Joshua Wiley wrote:
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
Hmisc has wtd.mean() and wtd.var() as well as a few other
weighted stats.
-Peter Ehlers
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?
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