Re: Calculate Standard Deviation with R


"Anon." <bob.ohara@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> a écrit dans le message de
news: f3ejpo$p8k$1@xxxxxxxxxxxxxxxxxxxxxxxxxx
R User wrote:
"Anon." <bob.ohara@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> a écrit dans le message
de news: f3e3tp$bon$1@xxxxxxxxxxxxxxxxxxxxxxxxxx
R User wrote:
Hello,

I begin with R and I am searching a way to calculate a ST of a weighed
serie :


xi(10,20,30)
ni(1,5,10)

I found the function VAR which uses a vector of one dimension but dot
not care about coefficients.

You could either write the function yourself, or use cov.wt:

x=rnorm(10)
wt=1:10
cov.wt(data.frame(x), wt)

I found this using help.search("weighted variance").

Ok thank you,

If I understand you affect a coefficient of 1 on the value 10 ?
But how do I do if I have several observations ?
I tried this :
x=rnorm(496,497,498,499,500,501,502,503,504))
Erreur : erreur de syntaxe dans
"x=rnorm(496,497,498,499,500,501,502,503,504))"

You have 2 closed brackets. And after that, rnorm() will still be
screwed: check its help page (?rnorm): I was only generating x and wt to
give an example of R working.

ok thank you,
could you confirm what I means : this not a miracle function which gives me
the standard deviation ?
Do I need to compute all intermediaries steps ?

How would you to calculate the standard deviation of a weighted serie like
this :
xi(5,6,8,9,10)
ni(1,5,3,2,6)

thank you for your help

Best regards
T

Bob

--
Bob O'Hara

Dept. of Mathematics and Statistics
P.O. Box 68 (Gustaf Hällströmin katu 2b)
FIN-00014 University of Helsinki
Finland

Telephone: +358-9-191 51479
Mobile: +358 50 599 0540
Fax: +358-9-191 51400
WWW: http://www.RNI.Helsinki.FI/~boh/
Journal of Negative Results - EEB: http://www.jnr-eeb.org


.

Relevant Pages