Hi [EMAIL PROTECTED] napsal dne 14.08.2007 15:11:11:
> Hello, > > I would like to do a large number of e.g. 1000 paired ttest using the by- > function. But instead of using only the data within the 1000 groups, R > caclulates 1000 times the ttest for the full data set(The same happens with > Wilcoxon test). However, the by-function works fine with the lme function. > Did I just miss something or is it really not working? If not, is there any > other possibility to avoid loops? > Thanks > Daniel > > Here is the R help example for "by" > require(stats) > attach(warpbreaks) > by(warpbreaks, tension, function(x) lm(breaks ~ wool, data = x)) > *->works great > by(warpbreaks,tension,function(x)t.test(breaks ~ wool,data=warpbreaks,paired = TRUE)) What about by(warpbreaks,tension,function(x)t.test(breaks ~ wool,data=x,paired = TRUE)) Regards Petr > *Same output for each level of tension: > > tension: L > > Paired t-test > > data: breaks by wool > t = 1.9956, df = 26, p-value = 0.05656 > alternative hypothesis: true difference in means is not equal to 0 > 95 percent confidence interval: > -0.1735803 11.7291358 > sample estimates: > mean of the differences > 5.777778 > > ------------------------------------------------------------------------ > > tension: M > > Paired t-test > > data: breaks by wool > t = 1.9956, df = 26, p-value = 0.05656 > alternative hypothesis: true difference in means is not equal to 0 > 95 percent confidence interval: > -0.1735803 11.7291358 > sample estimates: > mean of the differences > 5.777778 > > ------------------------------------------------------------------------ > > tension: H > > Paired t-test > > data: breaks by wool > t = 1.9956, df = 26, p-value = 0.05656 > alternative hypothesis: true difference in means is not equal to 0 > 95 percent confidence interval: > -0.1735803 11.7291358 > sample estimates: > mean of the differences > 5.777778 > > > > > > > > -- > > ______________________________________________ > R-help@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. ______________________________________________ R-help@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.