Thanks Tal. I modified my code based on your suggestion (below). It would be nice to see other solutions also. #### data ###### sam1 <- c(51.7, 54.2, 53.3, 57, 56.4, 61.5, 57.2, 56.2, 58.4, 55.8) sam2 <- c(62.5, 65.2, 67.6, 69.9, 69.4, 70.1, 67.8, 67, 68.5, 62.4) DF <- stack(data.frame(sam1 = sam1, sam2 = sam2))
#### paired-t-test ###### res <- t.test(values ~ ind, data=DF, paired = TRUE) #### plots ##### library(gregmisc) opar <- par(mfrow=c(1,2)) tapply(DF$values, list(DF$ind), ci) plotmeans(values ~ ind, data=DF) d <- sam1 - sam2 plot.ylim <- c(min(d, 0), max(d, 0)) abline(h = 0, lty = 2, col = "blue", lwd =2) stripchart(d, vertical=T, pch=16, ylim = plot.ylim ) points(1, res$estimate, col="red", pch=16) arrows(1, res$estimate, 1, res$conf.int[1], col="red", lwd=2, angle=90, length=0.1) arrows(1, res$estimate, 1, res$conf.int[2], col="red", lwd=2, angle=90, length=0.1) 2009/9/12 Tal Galili <tal.gal...@gmail.com> > Hello johannes, > > You're example looks nice and I am hoping to see more ideas from other > members. > > Just one tiny idea: > > In - > stripchart > Also use ylim to include the ZERO line (and then actually add the line) > like this: > > plot.ylim <- c(min(d, 0), max(d, 0)) > abline(h = 0, lty = 2, col = "blue", lwd =2) > > stripchart(d, vertical=T, pch=16, ylim = plot.ylim ) > > > This way you get to show how far you got the difference to be from the zero > (otherwise, all the graph gives is the variance, without any useful > knowledge of the distance of the differences from the zero) > > Also, consider using this function for CI plotting: > http://finzi.psych.upenn.edu/R/library/plotrix/html/plotCI.html > > > Best, > Tal Galili > > > > > > > > > On Sat, Sep 12, 2009 at 12:00 PM, johannes rara <johannesr...@gmail.com>wrote: > >> I would like to know if you have any suggestions how to visualize the >> results from a paired t-test (see the example data below). I tried to >> produce plots that show the mean and CI's from the original data and the >> estimate of the difference between means and the confidence intervals (see >> below) from the t-test. I really don't know what would be the best way to >> graphically display the results. Thanks in advance. >> #### data ###### >> sam1 <- c(51.7, 54.2, 53.3, 57, 56.4, 61.5, 57.2, 56.2, 58.4, 55.8) >> sam2 <- c(62.5, 65.2, 67.6, 69.9, 69.4, 70.1, 67.8, 67, 68.5, 62.4) >> DF <- stack(data.frame(sam1 = sam1, sam2 = sam2)) >> >> #### paired-t-test ###### >> >> res <- t.test(values ~ ind, data=DF, paired = TRUE) >> >> #### plots ##### >> library(gregmisc) >> >> opar <- par(mfrow=c(1,2)) >> tapply(DF$values, list(DF$ind), ci) >> plotmeans(values ~ ind, data=DF) >> >> d <- sam1 - sam2 >> stripchart(d, vertical=T, pch=16) >> points(1, res$estimate, col="red", pch=16) >> arrows(1, res$estimate, 1, res$conf.int[1], col="red", lwd=2, angle=90, >> length=0.1) >> arrows(1, res$estimate, 1, res$conf.int[2], col="red", lwd=2, angle=90, >> length=0.1) >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@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. >> > > > > -- > ---------------------------------------------- > > > My contact information: > Tal Galili > Phone number: 972-50-3373767 > FaceBook: Tal Galili > My Blogs: > http://www.r-statistics.com/ > http://www.talgalili.com > http://www.biostatistics.co.il > > > [[alternative HTML version deleted]] ______________________________________________ R-help@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.
