: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
project.org] On Behalf Of Ista Zahn
Sent: Tuesday, February 02, 2010 12:03 PM
To: Peng Yu
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] population variance and sample variance
Probably a simple typo, but just to keep things straight
To: Peng Yu
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] population variance and sample variance
Probably a simple typo, but just to keep things straight: you want to
divide by n when describing the standard deviation of a sample, and
divide by n-1 when estimating a population standard deviation
Zahn
Sent: Tuesday, February 02, 2010 12:03 PM
To: Peng Yu
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] population variance and sample variance
Probably a simple typo, but just to keep things straight: you want to
divide by n when describing the standard deviation of a sample, and
divide by n
on wiki for easy access
of some simple terms.
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
project.org] On Behalf Of Ista Zahn
Sent: Tuesday, February 02, 2010 12:03 PM
To: Peng Yu
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] population variance
, 2010 9:59 AM
To: Ista Zahn; Peng Yu
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] population variance and sample variance
Probably not a typo, but a different textbook used originally. Statistics
is still a relatively young science, so we have not settled on a single set
of notation/symbols/jargon
On Tue, Feb 2, 2010 at 10:25 AM, Peng Yu pengyu...@gmail.com wrote:
On Mon, Oct 19, 2009 at 12:53 PM, Kingsford Jones
kingsfordjo...@gmail.com wrote:
sum((x-mean(x))^2)/(n)
[1] 0.4894708
((n-1)/n) * var(x)
[1] 0.4894708
But this is not a built-in function in R to do so, right?
No because
the definition is context dependent.
Kingsford
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
project.org] On Behalf Of Ista Zahn
Sent: Tuesday, February 02, 2010 12:03 PM
To: Peng Yu
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] population variance
On Mon, Oct 19, 2009 at 12:53 PM, Kingsford Jones
kingsfordjo...@gmail.com wrote:
sum((x-mean(x))^2)/(n)
[1] 0.4894708
((n-1)/n) * var(x)
[1] 0.4894708
But this is not a built-in function in R to do so, right?
hth,
Kingsford
On Mon, Oct 19, 2009 at 9:30 AM, Peng Yu pengyu...@gmail.com
Probably a simple typo, but just to keep things straight: you want to
divide by n when describing the standard deviation of a sample, and
divide by n-1 when estimating a population standard deviation (your
initial description had it backwards I think).
On Tue, Feb 2, 2010 at 5:25 PM, Peng Yu
It seems that var() computes sample variance. It is straight forward
to compute population variance from sample variance. However, I feel
that it is still convenient to have a function that can compute
population variance. Is there a population variance function available
in R?
$ Rscript var.R
sum((x-mean(x))^2)/(n)
[1] 0.4894708
((n-1)/n) * var(x)
[1] 0.4894708
hth,
Kingsford
On Mon, Oct 19, 2009 at 9:30 AM, Peng Yu pengyu...@gmail.com wrote:
It seems that var() computes sample variance. It is straight forward
to compute population variance from sample variance. However, I feel
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