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Permutation Distribution
3 messages · Jacob van Wyk, Jacques VESLOT, Torsten Hothorn
data1 <- expand.grid(var1=1:15, var2=1:2)
> test <- replicate(1000, with(data.frame(var1=data1$var1, var2=sample(data1$var2)), diff(tapply(var1, var2, mean)))) > hist(test) ------------------------------------------------------------------- Jacques VESLOT CNRS UMR 8090 I.B.L (2?me ?tage) 1 rue du Professeur Calmette B.P. 245 59019 Lille Cedex Tel : 33 (0)3.20.87.10.44 Fax : 33 (0)3.20.87.10.31 http://www-good.ibl.fr ------------------------------------------------------------------- Jacob van Wyk a ?crit :
Hallo Is there an elegant way to do the following: Dataset consists of 2 variables: var1: some measurements, and var2: a grouping variable with two values, 1 and 2. There are (say) 10 measurements from group 1 and 15 measurements from group 2. The idea is to study the permutation distribution of mean(group 1) * mean(group2). One way would be to permute 1s and 2s and select the corresponding measurements; calculate the difference in means. Redo this 1000 times, say. Etc. Any help is much appreciated. Thanks Jacob Jacob L van Wyk Department of Statistics University of Johannesburg, APK P O Box 524 Auckland Park 2006 South Africa Tel: +27 11 489 3080 Fax: +27 11 489 2832 [[alternative HTML version deleted]]
______________________________________________ R-help at stat.math.ethz.ch 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.
On Thu, 20 Jul 2006, Jacob van Wyk wrote:
Hallo Is there an elegant way to do the following: Dataset consists of 2 variables: var1: some measurements, and var2: a grouping variable with two values, 1 and 2. There are (say) 10 measurements from group 1 and 15 measurements from group 2. The idea is to study the permutation distribution of mean(group 1) * mean(group2).
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
One way would be to permute 1s and 2s and select the corresponding measurements; calculate the difference in means.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
what test statistic do you want to use? Product or difference of means?
The latter one is easy:
library("coin")
independence_test(var1 ~ var2, data = <your data>, ...)
Torsten
Redo this 1000 times, say. Etc. Any help is much appreciated. Thanks Jacob Jacob L van Wyk Department of Statistics University of Johannesburg, APK P O Box 524 Auckland Park 2006 South Africa Tel: +27 11 489 3080 Fax: +27 11 489 2832 [[alternative HTML version deleted]]
______________________________________________ R-help at stat.math.ethz.ch 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.