R help - Apr 2012 - sdev, variance in prcomp

Hello,
It might be a trivial question but I just wanted to find out the relationship
between sdev and proportion of variance generated by prcomp. I got the following
result from my data set

???????????????????????????? PC1????? PC2????? PC3
Standard deviation???? 104.89454 15.40910 9.012047
Proportion of Variance?? 0.52344? 0.01130 0.003860
Cumulative Proportion??? 0.52344? 0.53474 0.538600



first, I had thought that the variance must be standard deviation power to 2 but
it seems that variance is sdev/200. Did I misunderstood some thing?

Best,

Carol

It is reporting _proportion_ of the total variance.  Not the variance.

The total variance is the sum of all the squared standard deviations.  Only
the first 3 standard deviations are shown.

Kevin


On Mon, Apr 9, 2012 at 3:31 PM, carol white <wht_crl@yahoo.com> wrote:
> Hello,
> It might be a trivial question but I just wanted to find out the
> relationship between sdev and proportion of variance generated by prcomp. I
> got the following result from my data set
>
>                              PC1      PC2      PC3
> Standard deviation     104.89454 15.40910 9.012047
> Proportion of Variance   0.52344  0.01130 0.003860
> Cumulative Proportion    0.52344  0.53474 0.538600
>
>
>
> first, I had thought that the variance must be standard deviation power to
> 2 but it seems that variance is sdev/200. Did I misunderstood some thing?
>
> Best,
>
> Carol
>
>
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>


-- 
Kevin Wright

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