[R] sample size for beta regression

2023-05-19 Thread greg holly
Hi all, Does anyone have experience estimating the sample size for beta regression? I have three treatment groups with 0.6, 0.5 and 0.3 mean of proportions. I tried use BetaPASS but failed, Regards, Greg [[alternative HTML version deleted]] __

Re: [R] Sample size Determination to Compare Three Independent Proportions

2021-08-11 Thread AbouEl-Makarim Aboueissa
Hi Marc: Thank you for your help in this matter. With thanks Abou On Tue, Aug 10, 2021, 9:28 AM Marc Schwartz wrote: > Hi, > > A search would suggest that there may not be an R function/package that > provides power/sample size calculations for the specific scenarios that > you are describi

Re: [R] Sample size Determination to Compare Three Independent Proportions

2021-08-10 Thread Marc Schwartz via R-help
Hi, A search would suggest that there may not be an R function/package that provides power/sample size calculations for the specific scenarios that you are describing. There may be something that I am missing, and there is also other dedicated software such as PASS (https://www.ncss.com/softw

Re: [R] Sample size Determination to Compare Three Independent Proportions

2021-08-10 Thread AbouEl-Makarim Aboueissa
Hi Marc: First, thank you very much for your help in this matter. Will perform an initial omnibus test of all three groups (e.g. 3 x 2 chi-square), possibly followed by all possible 2 x 2 pairwise comparisons (e.g. 1 versus 2, 1 versus 3, 2 versus 3), We can assume *either* the desired sample s

Re: [R] Sample size Determination to Compare Three Independent Proportions

2021-08-09 Thread Marc Schwartz via R-help
Hi, You are going to need to provide more information than what you have below and I may be mis-interpreting what you have provided. Presuming you are designing a prospective, three-group, randomized allocation study, there is typically an a priori specification of the ratios of the sample s

[R] Sample size Determination to Compare Three Independent Proportions

2021-08-09 Thread AbouEl-Makarim Aboueissa
Dear All: good morning *Re:* Sample Size Determination to Compare Three Independent Proportions *Situation:* Three Binary variables (Yes, No) Three independent populations with fixed sizes (*say:* N1 = 1500, N2 = 900, N3 = 1350). Power = 0.80 How to choose the sample sizes to compare th

Re: [R] Sample size required to estimate population variance

2019-07-05 Thread Stephen Ellison
> Thanks for the suggestion but I'm not sure that it answers my original > question.I need to know how many samples I need to collect to collect in > order to estimate the sample size needed to achieve a specific margin of > error for confidence intervals for the population variance. I'm not sure

Re: [R] Sample size required to estimate population variance

2019-07-04 Thread Thomas Subia via R-help
Thanks for the suggestion but I'm not sure that it answers my original question.I need to know how many samples I need to collect to collect in order to estimate the sample size needed to achieve a specific margin of error for confidence intervals for the population variance. I'm not sure wheth

Re: [R] Sample size required to estimate population variance

2019-07-04 Thread John via R-help
On Tue, 2 Jul 2019 22:23:18 + (UTC) Thomas Subia via R-help wrote: > Colleagues, > Can anyone suggest a package or code which might help me calculate > the minimum sample size required to estimate the population variance? > I can do this in Minitab but I'd rather do this in R. Thomas Subia Y

Re: [R] Sample size required to estimate population variance

2019-07-03 Thread ruipbarradas
just 1 but it will be zero.Hope this helps,Rui Barradas Enviado a partir do meu smartphone Samsung Galaxy. Mensagem original De: Thomas Subia via R-help Data: 02/07/2019 23:23 (GMT+00:00) Para: r-help@r-project.org Assunto: [R] Sample size required to estimate populatio

Re: [R] Sample size required to estimate population variance

2019-07-03 Thread ruipbarradas
homas Subia via R-help Data: 02/07/2019 23:23 (GMT+00:00) Para: r-help@r-project.org Assunto: [R] Sample size required to estimate population variance Colleagues,Can anyone suggest a package or code which might help me calculate the minimum sample size required to estimate the population varianc

Re: [R] Sample size required to estimate population variance

2019-07-02 Thread Richard O'Keefe
Does this help? https://www.r-bloggers.com/computing-sample-size-for-variance-estimation/ On Wed, 3 Jul 2019 at 10:23, Thomas Subia via R-help wrote: > Colleagues, > Can anyone suggest a package or code which might help me calculate the > minimum sample size required to estimate the population v

[R] Sample size required to estimate population variance

2019-07-02 Thread Thomas Subia via R-help
Colleagues, Can anyone suggest a package or code which might help me calculate the minimum sample size required to estimate the population variance? I can do this in Minitab but I'd rather do this in R. Thomas Subia [[alternative HTML version deleted]] ___

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]] __

Re: [R] Sample size using residual standard deviation

2017-04-12 Thread peter dalgaard
Or power.t.test() -pd > On 12 Apr 2017, at 18:44 , Bert Gunter wrote: > > Search "sample size power" on rseek.org. Many useful hits, including > "samplesize" package. > > -- Bert > > > Bert Gunter > > "The trouble with having an open mind is that people keep coming along > and sticking thin

Re: [R] Sample size using residual standard deviation

2017-04-12 Thread Bert Gunter
Search "sample size power" on rseek.org. Many useful hits, including "samplesize" package. -- 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 Wed, Apr 12

Re: [R] Sample size using residual standard deviation

2017-04-12 Thread David Winsemius
> On Apr 12, 2017, at 3:20 AM, Jomy Jose wrote: > > In R how to calculate sample size,where power,residual standard deviation > and treatment difference is given.? Use the non-central t-distribution. The help page has further advice: ?pt > > [[alternative HTML version deleted]] Pleas

[R] Sample size using residual standard deviation

2017-04-12 Thread Jomy Jose
In R how to calculate sample size,where power,residual standard deviation and treatment difference is given.? [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/

[R] Sample size for clustering analysis?

2013-11-05 Thread Li, Yan
Hi All, What formula can I use to determine the right sample size for clustering analysis with 100-300 variables? What sampling methodology can be used for k-means or hierarchical clustering on categorical fields so that all values of the categorical fields are included in the sample? Thanks

Re: [R] sample size determination - comparing means for different size samples

2013-06-07 Thread Rui Barradas
Hello, At an R prompt, type ?power.t.test Hope this helps, Rui Barradas Em 06-06-2013 20:58, Rebecca Greenblatt escreveu: Looking to determine sample sizes for both my experimental and control groups (I want only a small portion of my participants in my experimental condition) in order to co

Re: [R] sample size determination - comparing means for different size samples

2013-06-06 Thread David Winsemius
This is a duplicate question, right? On Jun 6, 2013, at 12:58 PM, Rebecca Greenblatt wrote: > Looking to determine sample sizes for both my experimental and control > groups (I want only a small portion of my participants in my experimental > condition) in order to compare population means. I wou

[R] sample size determination - comparing means for different size samples

2013-06-06 Thread Rebecca Greenblatt
Looking to determine sample sizes for both my experimental and control groups (I want only a small portion of my participants in my experimental condition) in order to compare population means. I would be able to estimate standard deviation beforehand. I'm using the bpower function from the Hmisc

Re: [R] sample size in box plot labels

2013-04-26 Thread PIKAL Petr
.@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Shane Carey > Sent: Friday, April 26, 2013 1:09 PM > To: Rui Barradas > Cc: r-help@r-project.org > Subject: Re: [R] sample size in box plot labels > > This works, great. Cheers > > > On Fri, Apr 2

Re: [R] sample size in box plot labels

2013-04-26 Thread Shane Carey
This works, great. Cheers On Fri, Apr 26, 2013 at 12:02 PM, Rui Barradas wrote: > Hello, > > To count the sample sizes for each factor try > > tapply(DATA$K_Merge, DATA$UnitName_1, FUN = length) > > > Hope this helps, > > Rui Barradas > > Em 26-04-2013 10:48, Shane Carey escreveu: > > Hi, >> >

Re: [R] sample size in box plot labels

2013-04-26 Thread Rui Barradas
Hello, To count the sample sizes for each factor try tapply(DATA$K_Merge, DATA$UnitName_1, FUN = length) Hope this helps, Rui Barradas Em 26-04-2013 10:48, Shane Carey escreveu: Hi, I would like to put the sample number beside each lable in a boxplot. How do I do this? Essentially, I need

Re: [R] sample size in box plot labels

2013-04-26 Thread PIKAL Petr
Hi > -Original Message- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Shane Carey > Sent: Friday, April 26, 2013 11:49 AM > To: r-help@r-project.org > Subject: [R] sample size in box plot labels > > Hi, > >

[R] sample size in box plot labels

2013-04-26 Thread Shane Carey
Hi, I would like to put the sample number beside each lable in a boxplot. How do I do this? Essentially, I need to count the sample size for each factor, see below: Thanks boxplot(DATA$K_Merge~factor(DATA$UnitName_1),axes=FALSE,col=colours) title(main=list("Tukey Boxplot by Geology:\n K(%)",cex=c

[R] R: sample size package

2012-02-03 Thread IOANNA
Hello, Lets assume I have an ordinal response variable representing the D<-c(D0,D1,D2,D3,D4) where D0 is no damage and D4 is collapse which I want to correlate with a continuous predictor variable, wind speed at the location of each building. is there a function in R which I can use to es

[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

Re: [R] Sample size calculations for one sided binomial exact test

2011-11-03 Thread Marc Schwartz
From: https://stat.ethz.ch/pipermail/r-help/2011-November/294329.html > I'm trying to compute sample size requirements for a binomial exact test. > we want to show that the proportion is at least 90% assuming that it is > 95%, with 80% power so any asymptotic approximations are out of the > quest

[R] Sample size calculations for one sided binomial exact test

2011-11-01 Thread Andrew Redd
I'm trying to compute sample size requirements for a binomial exact test. we want to show that the proportion is at least 90% assuming that it is 95%, with 80% power so any asymptotic approximations are out of the questions. I was planning on using binom.test to perform the simple test against a

[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 AUC for ROC curves

2011-08-14 Thread Karl Knoblick
but I am confused a little Karl  - Ursprüngliche Mail Von: David Winsemius An: Karl Knoblick CC: Greg Snow ; "r-h...@stat.math.ethz.ch" Gesendet: Samstag, den 13. August 2011, 2:18:37 Uhr Betreff: Re: [R] Sample size AUC for ROC curves On Aug 11, 2011, at 5:50 AM, Kar

Re: [R] Sample size AUC for ROC curves

2011-08-12 Thread David Winsemius
- Ursprüngliche Mail Von: Greg Snow An: Karl Knoblick ; "r-h...@stat.math.ethz.ch" Gesendet: Dienstag, den 9. August 2011, 19:45:12 Uhr Betreff: RE: [R] Sample size AUC for ROC curves If you know how to generate random data that represents your null hypothesis (chance, auc=0.5) and

Re: [R] Sample size AUC for ROC curves

2011-08-11 Thread Karl Knoblick
Von: Greg Snow An: Karl Knoblick ; "r-h...@stat.math.ethz.ch" Gesendet: Dienstag, den 9. August 2011, 19:45:12 Uhr Betreff: RE: [R] Sample size AUC for ROC curves If you know how to generate random data that represents your null hypothesis (chance, auc=0.5) and how to do your anal

Re: [R] Sample size AUC for ROC curves

2011-08-09 Thread Greg Snow
nces@r- > project.org] On Behalf Of Karl Knoblick > Sent: Monday, August 08, 2011 3:29 PM > To: r-h...@stat.math.ethz.ch > Subject: [R] Sample size AUC for ROC curves > > Hallo! > > Does anybody know a way to calculate the sample size for comparing AUC > of ROC > curves a

[R] Sample size AUC for ROC curves

2011-08-08 Thread Karl Knoblick
Hallo! Does anybody know a way to calculate the sample size for comparing AUC of ROC curves against 'by chance' with AUC=0.5 (and/or against anothe AUC)? Thanks! Karl __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PL

Re: [R] Sample size estimation for sample surveys

2011-04-04 Thread Thomas Levine
Awesome! Thanks, David and Dennis! And now I know how to search for packages more effectively. Tom On Mon, Apr 4, 2011 at 9:38 PM, Dennis Murphy wrote: > Start here: > > library(sos)  # install first if necessary > findFn('sample size survey') > > I got 238 hits, many of which could be relev

Re: [R] Sample size estimation for sample surveys

2011-04-04 Thread Dennis Murphy
Start here: library(sos) # install first if necessary findFn('sample size survey') I got 238 hits, many of which could be relevant. HTH, Dennis On Mon, Apr 4, 2011 at 6:05 PM, Thomas Levine wrote: > Hi, > > Is there an R package for estimating sample size requirements for > parameter esti

[R] Sample size estimation for sample surveys

2011-04-04 Thread Thomas Levine
Hi, Is there an R package for estimating sample size requirements for parameter estimation in sample surveys? In particular, I'm interested in sample size estimation for stratified and systematic sampling. I have a textbook with appropriate formulae, but it'd be nice if I didn't have to type in al

Re: [R] Sample size of longitudinal and skewed data

2011-03-23 Thread Greg Snow
t.org] On Behalf Of Lao Meng > Sent: Monday, March 21, 2011 1:20 AM > To: R help > Subject: [R] Sample size of longitudinal and skewed data > > Hi all: > I have a question about the sample size calculation. > > It's a pilot study,which includes 2 groups(low,high),3 t

[R] Sample size of longitudinal and skewed data

2011-03-21 Thread Lao Meng
Hi all: I have a question about the sample size calculation. It's a pilot study,which includes 2 groups(low,high),3 time point(3,6,9 monthes).Each person has 3 results which according to the 3 time points.So it's a longitudinal study. I want to calculate the minimum sample size from the pilot st

Re: [R] sample size of 2 groups of skewed data

2011-03-15 Thread Kjetil Halvorsen
did you try to fit your data with a skew-normal/skew-t distribution? If that works, you can use simulation. Kjetil On Tue, Mar 15, 2011 at 2:31 AM, Lao Meng wrote: > Hi all: > I have a question on sample size calculation of 2 groups of data. If 2 > groups of data are all normal distribution, the

[R] sample size of 2 groups of skewed data

2011-03-14 Thread Lao Meng
Hi all: I have a question on sample size calculation of 2 groups of data. If 2 groups of data are all normal distribution, then I can use the function "n.indep.t.test.eq" from samplesize package.But if 2 groups of data are all skewed distribution, but not normal distribution,how can I calculate the

Re: [R] Sample size with ANCOVA

2010-11-20 Thread Marc Schwartz
On Nov 20, 2010, at 8:31 AM, XINLI LI wrote: > Dear R users: > > How to calculate the sample size with ANCOVA? For example, in a > clinical trial, the correlation between the baseline and one-year follow-up > blood pressure is 0.7, with a standrad devision 15, in order to detect a 10 > d

[R] Sample size with ANCOVA

2010-11-20 Thread XINLI LI
Dear R users: How to calculate the sample size with ANCOVA? For example, in a clinical trial, the correlation between the baseline and one-year follow-up blood pressure is 0.7, with a standrad devision 15, in order to detect a 10 difference between baseline and follow-up with a power = 0

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 estimation for non-inferiority log-rank and Wilcoxon rank-sum tests

2010-09-27 Thread Peter Dalgaard
On 09/27/2010 08:09 PM, Paul Miller wrote: > Hello Everyone, > > I'm trying to conduct a couple of power analyses and was hoping > someone might be able to help. I want to estimate the sample size > that would be necessary to adequately power a couple of > non-inferiority tests. The first would b

Re: [R] Sample size estimation for non-inferiority log-rank and Wilcoxon rank-sum tests

2010-09-27 Thread Andrew Miles
I haven't done much with the type of data you're working with, but here is a post that lists a few packages for doing sample size calculations in R. Perhaps one of them will be helpful. https://stat.ethz.ch/pipermail/r-help/2008-February/154223.html Andrew Miles On Sep 27, 2010, at 2:09 PM,

[R] Sample size estimation for non-inferiority log-rank and Wilcoxon rank-sum tests

2010-09-27 Thread Paul Miller
Hello Everyone,   I'm trying to conduct a couple of power analyses and was hoping someone might be able to help. I want to estimate the sample size that would be necessary to adequately power a couple of non-inferiority tests. The first would be a log-rank test and the second would be a Wilcoxon

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

Re: [R] Sample size ANCOVA

2010-07-14 Thread Marc Schwartz
On Jul 14, 2010, at 6:13 AM, Karl Knoblick wrote: > Hallo! > > Does anyone know a possibility to perform a sample size estimation for an > ANCOVA? Would be great! > > > Thanks > Karl I don't know of a function in R that performs this directly. However, if you Google: http://lmgtfy.com/?

[R] Sample size ANCOVA

2010-07-14 Thread Karl Knoblick
Hallo! Does anyone know a possibility to perform a sample size estimation for an ANCOVA? Would be great! Thanks Karl __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-pr

Re: [R] sample size for survival curves

2010-05-06 Thread array chip
Thanks Kevin. I thought the time t is at the end of follow-up (length of follow-up)? John --- On Thu, 5/6/10, Kevin E. Thorpe wrote: > From: Kevin E. Thorpe > Subject: Re: [R] sample size for survival curves > To: "array chip" > Cc: r-help@r-project.org > Date: Th

Re: [R] sample size for survival curves

2010-05-06 Thread array chip
p1=0.8 and p2=0.6 at 5 years at 5% significance level with 80% power" any comments are appreciated.   John --- On Thu, 5/6/10, Joris Meys wrote: From: Joris Meys Subject: Re: [R] sample size for survival curves To: "array chip" Date: Thursday, May 6, 2010, 8:12 PM

Re: [R] sample size for survival curves

2010-05-06 Thread Frank E Harrell Jr
On 05/06/2010 07:20 PM, Kevin E. Thorpe wrote: array chip wrote: Dear R users, I am not asking questions specifically on R, but I know there are many statistical experts here in the R community, so here it goes my questions: Freedman (1982) propose an approximation of sample size/power calculat

Re: [R] sample size for survival curves

2010-05-06 Thread Kevin E. Thorpe
array chip wrote: Dear R users, I am not asking questions specifically on R, but I know there are many statistical experts here in the R community, so here it goes my questions: Freedman (1982) propose an approximation of sample size/power calculation based on log-rank test using the formula b

[R] sample size for survival curves

2010-05-06 Thread array chip
Dear R users, I am not asking questions specifically on R, but I know there are many statistical experts here in the R community, so here it goes my questions: Freedman (1982) propose an approximation of sample size/power calculation based on log-rank test using the formula below (This is what n

Re: [R] sample size > 20K? Was: fitness of regression tree: how tomeasure???

2010-04-05 Thread Liaw, Andy
Just to follow up on Bert's and Frank's excellent comments. I'm continued to be amazed by people trying to interpret a single tree. Besides the variability in the tree structure (try bootstrapping and see how the trees change), it is difficult to make sense of splits more than a few levels down (h

Re: [R] sample size > 20K? Was: fitness of regression tree: how to measure???

2010-04-01 Thread Ravi Varadhan
10 12:55 pm Subject: Re: [R] sample size > 20K? Was: fitness of regression tree: how to measure??? To: 'Frank E Harrell Jr' , 'vibha patel' Cc: r-help@r-project.org > Since Frank has made this somewhat cryptic remark (sample size > 20K) > several times now, per

Re: [R] sample size > 20K? Was: fitness of regression tree: how to measure???

2010-04-01 Thread Frank E Harrell Jr
Good comments Bert. Just 2 points to add: People rely a lot on the tree structure found by recursive partitioning, so the structure needs to be stable. This requires a huge samples size. Second, recursive partitioning is not competitive with other methods in terms of predictive descriminatio

Re: [R] sample size > 20K? Was: fitness of regression tree: how to measure???

2010-04-01 Thread hadley wickham
> Incidentally, there is nothing new or radical in this; indeed, John Tukey, > Leo Breiman, George Box, and others wrote eloquently about this decades ago. > And Breiman's random forest modeling procedure explicitly abandoned efforts > to build simply interpretable models (from which one might infe

Re: [R] sample size > 20K? Was: fitness of regression tree: how to measure???

2010-04-01 Thread Bert Gunter
Since Frank has made this somewhat cryptic remark (sample size > 20K) several times now, perhaps I can add a few words of (what I hope is) further clarification. Despite any claims to the contrary, **all** statistical (i.e. empirical) modeling procedures are just data interpolators: that is, all t

[R] sample size mixed poisson glm

2010-03-25 Thread caspar hallmann
Dear list members, I am trying to estimate power/sample size based on already collected pilot data. The setting: Five orchards have been sampled with respect to fruit damage. In each orchard two plots were selected (semi-randomly), where one was treated and one left as control. Within each plot a

Re: [R] Sample size for proportion, not binomial

2010-03-24 Thread Prew, Paul
Dear Marc, Thank you very much for the advice and the papers, it helps. Regards, Paul From: >Marc Schwartz To: "Prew, Paul" Cc: r-help@r-project.org Subject: Re: [R] Sample size for proportion, not binomial Message-ID: Content-Type: text/plain; charset=windows-1252 On Mar 23

Re: [R] Sample size for proportion, not binomial

2010-03-23 Thread Marc Schwartz
On Mar 23, 2010, at 11:05 AM, Prew, Paul wrote: > Hello, I am looking for a sample size function for samples sizes, to test > proportions that are not binomial proportions. The proportions represent a > ratio of (final measure) / (baseline measure) on the same experimental unit. > Searches u

[R] Sample size for proportion, not binomial

2010-03-23 Thread Prew, Paul
Hello, I am looking for a sample size function for samples sizes, to test proportions that are not binomial proportions. The proportions represent a ratio of (final measure) / (baseline measure) on the same experimental unit. Searches using RSeek and such bring multiple hits for binomial prop

[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 - proportion continuity correction

2009-06-02 Thread Frank E Harrell Jr
Karl Knoblick wrote: Hallo! Does anybody know how to calculate a sample size estimation for proportions with continuity correction? That would lose power. Frank I only found EpiR which seems to calculate without continuity correction: library(epiR) epi.studysize(treat = .65, control = .

[R] Sample size: epiR survival

2009-06-02 Thread Karl Knoblick
Hallo! Does anybody know what epiR calculates with method = "survival"? library(epiR) library(survival) epi.studysize(treat = .65, control = .50, n = NA, sigma = NA, power = 0.80, r = 1, conf.level = 0.95, sided.test = 2, method = "survival") Because I found out that method "proportion" does n

[R] Sample size - proportion continuity correction

2009-06-02 Thread Karl Knoblick
Hallo! Does anybody know how to calculate a sample size estimation for proportions with continuity correction?   I only found EpiR which seems to calculate without continuity correction: library(epiR) epi.studysize(treat = .65, control = .50, n = NA, sigma = NA, power = 0.80, r = 1, conf.level

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

Re: [R] sample size estimation for count (poisson?) data?

2008-11-13 Thread Shawn Morrison
Thanks. I did the search before I posted and found those threads. However, it does not seem to do what I want. All I want to do is estimate the sample size for a point estimate, not do a GLM. I just want the mean within a margin of error, and to a given CI. I've tried writing some code to do

Re: [R] sample size estimation for count (poisson?) data?

2008-11-13 Thread David Winsemius
The notion that you can just add or subtract 0.03 from estimate is obviously incorrect. Presuming you meant to call you lower bound q05 and the upper bound q95, the numbers I get are in your 10,000 iteration loop are 4.97 and 5.18 (around a mean of 5.08). So roughly a .1 swing on each side

Re: [R] sample size estimation for count (poisson?) data?

2008-11-12 Thread David Winsemius
The first hit for search on "sample size" and "poisson" on Baron's search engine web interface appears on target: http://search.r-project.org/cgi-bin/namazu.cgi?query=%22sample+size%22+poisson&max=100&result=normal&sort=score&idxname=functions&idxname=Rhelp02a Getting the same result from your

[R] sample size estimation for count (poisson?) data?

2008-11-12 Thread Shawn Morrison
Is there a function in R that will allow me to estimate the sample size required from count data (poisson data?), given the known variance and desired margin of error and confidence interval? My specific data set will be based on a survey of hikers that will be asked about the number of anim

Re: [R] sample size in bootstrap(boot)

2008-06-08 Thread Tim Hesterberg
> > -Original Message- > > > From: [EMAIL PROTECTED] > > > [mailto:[EMAIL PROTECTED] On Behalf Of Zaihra T > > > Sent: Wednesday, March 26, 2008 7:57 AM > > > To: Jan T. Kim; R-help@r-project.org > > > Subject: ! [R] sample size in

[R] Sample size for 2-sample proportion tests

2008-05-28 Thread Karl Knoblick
Hallo! I found a question exactly as mine, but I did not found an answer. Therefore I post this again - hopefully there will be an answer! Thanks in advance! karl From: Berta Date: Tue, 27 Feb 2007 18:58:48 +0100 Hi R-users, I want to calculate the sample size needed to carry out a 2-sample p

Re: [R] sample size for log-rank test with more than 2 groups

2008-04-08 Thread Frank E Harrell Jr
Essioux, Laurent wrote: > Hi everyone, > > I was wondering whether extension of the current spower function for > Hmisc were existing? > > My current focus is to calculate sample size based on the log-rank test > with more than 2 groups (with/without trend) > > Taking into account the loss of fo

[R] sample size for log-rank test with more than 2 groups

2008-04-08 Thread Essioux, Laurent
Hi everyone, I was wondering whether extension of the current spower function for Hmisc were existing? My current focus is to calculate sample size based on the log-rank test with more than 2 groups (with/without trend) Taking into account the loss of follow up and the accrual processes. A SPSS

Re: [R] sample size in bootstrap(boot)

2008-03-26 Thread Nordlund, Dan (DSHS/RDA)
6 AM To: Nordlund, Dan (DSHS/RDA); Jan T. Kim; R-help@r-project.org Subject: Re: [R] sample size in bootstrap(boot) Hi Dan, Thanks for response yes i do know that bootstrap samples generated by function boot are of the same size as original dataset but s

Re: [R] sample size in bootstrap(boot)

2008-03-26 Thread Zaihra T
"Nordlund, Dan (DSHS/RDA)" wrote: > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Zaihra T > > Sent: Wednesday, March 26, 2008 7:57 AM > > To: Jan T. Kim; R-help@r-project.org > >

Re: [R] sample size in bootstrap(boot)

2008-03-26 Thread Nordlund, Dan (DSHS/RDA)
> -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Zaihra T > Sent: Wednesday, March 26, 2008 7:57 AM > To: Jan T. Kim; R-help@r-project.org > Subject: [R] sample size in bootstrap(boot) > > >Hi, > >Can some

[R] sample size in bootstrap(boot)

2008-03-26 Thread Zaihra T
Hi, Can someone tell me how to control sample size (n) in bootstrap function boot in R. Can we give some option like we give for # of repeated samples(R=say 100). Will appreciate any help. thanks __ R-help@r-project.org mailing

[R] Sample size for reference data (with covariate)

2007-10-05 Thread Karl Knoblick
Hello! Is there a possibilty in R to calculate the sample size for evaluation of reference values? Especially reference values with a covariate age and a factor gender? Any help will be appreciated. Thanks! Karl Heute schon einen Blick in die Zukunft von E-Mails wagen?

[R] Sample size

2007-09-27 Thread motaveiga
Hi for all. How can I determinate in R the sample size to estimate a logistic regression with two outcomes. One of outcomes was 47% in population and I want determine the factors that influence that probability. Thanks everyone __ R-help@r-project