Re: [R] Sample size calculation for three-way incomplete block crossover study.

2017-09-05 Thread Bert Gunter
Sounds like a homework problem. This list has a no homework policy if it is. -- Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Mon, Sep 4, 2017 at 10:31

[R] Sample size calculation for three-way incomplete block crossover study.

2017-09-04 Thread Jomy Jose
Hi In R,how to do sample size calculation for three-way incomplete block crossover study where within subject residual standard deviation,treatment difference and power is given. Thanks in advance. Regards Jose [[alternative HTML version deleted]] __

[R] Sample Size Calculation

2011-11-22 Thread sr500
Hi, I'm trying to determine a sample size calculation for a mock RCT. I want to compare the event rate (proportion) between two unequal groups. Thanks! -- View this message in context: http://r.789695.n4.nabble.com/Sample-Size-Calculation-tp4098429p4098429.html Sent from the R help mailing l

[R] Sample Size Calculation using a Drop the Loser/Keep the Winner Design

2011-09-26 Thread Paul Miller
Hello Everyone,   I need to perform a sample size calculation using a drop the loser/keep the winner design. I've been searching for examples of how to do this using R but haven't found much.   The most promising possibility thus far is an R function called DrpLsrNRst. This appears in the book

Re: [R] Sample size calculation for differences between two very small proportions (Fisher's exact test or others)?

2010-11-08 Thread David Winsemius
So that a bit lower than the 77 above but implies that 42,207 would be needed. -- David. > > Thanks a lot everybody again for your suggestions, > if anybody has other comments, they are always welcome. > > Best, > > Giulio > > > > Subject: Re: [R] Sample size c

Re: [R] Sample size calculation for differences between two very small proportions (Fisher's exact test or others)?

2010-11-08 Thread Giulio Di Giovanni
ybody again for your suggestions, if anybody has other comments, they are always welcome. Best, Giulio > Subject: Re: [R] Sample size calculation for differences between two very > small proportions (Fisher's exact test or others)? > From: marc_schwa...@me.com > Date: Mon, 8 Nov

Re: [R] Sample size calculation for differences between two very small proportions (Fisher's exact test or others)?

2010-11-08 Thread Marc Schwartz
Hi, I don't have access to the article, but must presume that they are doing something "radically different" if you are "only" getting a total sample size of 20,000. Or is that 20,000 per arm? Using the G*Power app that Mitchell references below (which I have used previously, since they have a

Re: [R] Sample size calculation for differences between two very small proportions (Fisher's exact test or others)?

2010-11-08 Thread David Winsemius
On Nov 8, 2010, at 11:16 AM, Mitchell Maltenfort wrote: Not with R, Really? require(sos) findFn("power exact test") found 54 matches; retrieving 3 pages 2 3 These look on point: http://finzi.psych.upenn.edu/R/library/statmod/html/power.html http://finzi.psych.upenn.edu/R/library/binom/htm

Re: [R] Sample size calculation for differences between two very small proportions (Fisher's exact test or others)?

2010-11-08 Thread Mitchell Maltenfort
Not with R, but look for G*Power3, a free tool for power calc, includes FIsher's test. http://www.psycho.uni-duesseldorf.de/abteilungen/aap/gpower3 On Mon, Nov 8, 2010 at 10:52 AM, Giulio Di Giovanni wrote: > > > Hi, > I'm try to compute the minimum sample size needed to have at least an 80% of

[R] Sample size calculation for differences between two very small proportions (Fisher's exact test or others)?

2010-11-08 Thread Giulio Di Giovanni
Hi, I'm try to compute the minimum sample size needed to have at least an 80% of power, with alpha=0.05. The problem is that empirical proportions are really small: 0.00154 in one case and 0.00234. These are the estimated failure proportion of two medical treatments. Thomas and Conlon (1992)

Re: [R] Sample size calculation for non-normal population with unknown mean and SD

2010-07-26 Thread Bert Gunter
The obvious: Take a small sample, say 25-50.  Get an estimate of your distribution from that. Then use this to determine how many more (if any) additional samples you need for desired precision. This latter can probably easily be done via simulation/bootstrap if you don't want to specify a paramet

[R] Sample size calculation for non-normal population with unknown mean and SD

2010-07-26 Thread Majonu
Basically, we have a population of 4,392 documents and we want to find out the number of patents per document. We don’t want to go through all 4,392 documents, but want a reliable sample size from which to draw inferences. I feel like this count data will not follow a normal distribution, but more

[R] Sample size calculation for paired proportion testing?

2009-11-21 Thread xiaojun ma
I would appreciate any help on this problem. I need to perform a sample size analysis for a study comparing the performances of 2 different methods of diagnostic classification. Assume that method 1 has an accuracy of p1 against known truths (a reference classification, as multiple categories), an

Re: [R] Sample size calculation proportions with EpiR: Discrepancy to other calculators

2009-06-02 Thread Karl Knoblick
ath.ethz.ch Gesendet: Dienstag, den 26. Mai 2009, 16:43:09 Uhr Betreff: Re: [R] Sample size calculation proportions with EpiR: Discrepancy to other calculators On Tue, 26 May 2009, Chuck Cleland wrote: > On 5/26/2009 2:53 AM, Karl Knoblick wrote: >> Hallo! >> >> I have done a sam

Re: [R] Sample size calculation proportions with EpiR: Discrepancy to other calculators

2009-05-26 Thread Thomas Lumley
On Tue, 26 May 2009, Chuck Cleland wrote: On 5/26/2009 2:53 AM, Karl Knoblick wrote: Hallo! I have done a sample size calculation for proportions with EpiR. The input is: treatment group rate p=0.65 control group rate p=0.50 significance level 0.95 power 0.80 two-sided ration group 1 and 2: 1.

Re: [R] Sample size calculation proportions with EpiR: Discrepancy to other calculators

2009-05-26 Thread Chuck Cleland
On 5/26/2009 2:53 AM, Karl Knoblick wrote: > Hallo! > > I have done a sample size calculation for proportions with EpiR. The input is: > treatment group rate p=0.65 > control group rate p=0.50 > significance level 0.95 > power 0.80 > two-sided > ration group 1 and 2: 1.0 > > I have done this in t

[R] Sample size calculation proportions with EpiR: Discrepancy to other calculators

2009-05-26 Thread Karl Knoblick
Hallo! I have done a sample size calculation for proportions with EpiR. The input is: treatment group rate p=0.65 control group rate p=0.50 significance level 0.95 power 0.80 two-sided ration group 1 and 2: 1.0 I have done this in the following way: library(epiR) epi.studysize(treat = 0.65, cont