[R] Mean from confidence intervals

Joshua Wiley jwiley.psych at gmail.com
Sat Jan 29 03:16:46 CET 2011

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:


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 :)



On Fri, Jan 28, 2011 at 2:15 PM, Peter Francis <peterfrancis at 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
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles

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