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
On Jan 28, 2011, at 5:15 PM, Peter Francis 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 ?If a Gaussian distribution were assumed, then wouldn't the symmetry of that distribution be a huge clue? (Making me think this to be homework.) -- David Winsemius, MD West Hartford, CT
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 <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 > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > 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 http://www.joshuawiley.com/
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. However the script i used, output q0.005 q0.01 etc upto q0.995 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 <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 > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > 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 http://www.joshuawiley.com/
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 q0.995Those 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 <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 >> >> PeterDavid Winsemius, MD West Hartford, CT
Em 28/1/2011 20:15, Peter Francis escreveu:> 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, Just a question others have not put forward, but that puzzles me: the confidence intervals are for the estimation of what? Why you have the 'n' (which I surmise it's being understood as "the number of samples") and a two tailed confidence intervals, and lastly what does the p value reports?