On Jan 29, 2011, at 9:39 AM, Peter Francis wrote:
Dear all,
The data is generated from 1000 random samples of a phylogenetic
tree to calculate phylogenetic diversity. I sampled the tree 1000
times at with various species communities (600) to get a random PD
per community. I then want to test my observed PD with that of a
random sample to test for significance.
Color me puzzled. I thought you already had a test (the p value) and
you wanted an estimate for a mean given that you had a 95% CI.
However the script i used, output
q0.005 q0.01 etc upto q0.995
Those look like names or labels for quantiles. This would move along a
lot faster if you gave a more complete listing of the output and the
code used to generate it.
--
David.
But i wanted to know the mean PD value per community based on the
output, and that is where i am struggling
Thanks,
Peter
On 29 Jan 2011, at 02:16, Joshua Wiley wrote:
Hi Peter,
Do you know the formula used to calculate the confidence interval? I
suspect it is possible with minimal algebraic manipulation of the CI
formula to find what the mean is. Assuming a normal distribution (as
David), then it is certainly possible to find. This wikipedia page
might help:
http://en.wikipedia.org/wiki/Confidence_interval
And no, this is not really the correct place to ask. My basic rule of
thumb is, "Does my question have anything to do with R? If my answer
is, "No." then I usually look for somewhere else to post. Of course,
for a comprehensive list, see the posting guide.
If you are wondering if there is a function to do it for you, I am not
sure, but it would be trivial to programme and if you show us the
formula for it (the mean from the CI), we can certainly give you
pointers for how to write your own :)
Cheers,
Josh
On Fri, Jan 28, 2011 at 2:15 PM, Peter Francis <peterfran...@me.com>
wrote:
Dear List,
I am not sure if A) this is possible or B) the correct place to ask.
I am looking to find the mean - i have n, and the two-tailed
confidence intervals 0.95 & 0.25 with a p-value of 0.05.
Can i find the mean from this data ?
Thanks
Peter
David Winsemius, MD
West Hartford, CT
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