[R] how to perform multiple comparison？
Hi all: As to the anova, we can perform multiple comparison via TukeyHSD. But as to chi-square test for frequency table,how to perform multiple comparison? For example, if I want to compare 3 samples' ratio(the data has 3 rows,each row corresponds to 1 sample,and has 2 columns,each column corresponds to positive and negative respectively). dat<-matrix(c(6,30,8,23,14,3),nrow=3) dat [,1] [,2] [1,]6 23 [2,] 30 14 [3,]83 chisq.test(dat) Pearson's Chi-squared test data: dat X-squared = 17.9066, df = 2, p-value = 0.0001293 The result shows that the difference between the 3 samples is significant.But if I want to perform multiple comparison to find out which pair of samples is significantly different,which function should be used? Many thanks for your help. My best ��ʦ [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] how to perform multiple comparison？
thanks for your help. 发自 网易邮箱大师 On 2016-05-20 09:48 , David Winsemius Wrote: > On May 19, 2016, at 5:19 PM, Jim Lemon wrote: > > Hi laomeng_3, > Have a look at the padjust function (stats). > > Jim > > > On Fri, May 20, 2016 at 1:56 AM, laomeng_3 wrote: >> Hi all: >> As to the anova, we can perform multiple comparison via TukeyHSD. >> But as to chi-square test for frequency table,how to perform multiple >> comparison? >> >> For example, if I want to compare 3 samples' ratio(the data has 3 rows,each >> row corresponds to 1 sample,and has 2 columns,each column corresponds to >> positive and negative respectively). >> >> >> dat<-matrix(c(6,30,8,23,14,3),nrow=3) >> dat >> [,1] [,2] >> [1,]6 23 >> [2,] 30 14 >> [3,]83 >> >> >> >> chisq.test(dat) >> >> Pearson's Chi-squared test >> >> data: dat >> X-squared = 17.9066, df = 2, p-value = 0.0001293 >> >> >> The result shows that the difference between the 3 samples is >> significant.But if I want to perform multiple comparison to find out which >> pair of samples is significantly different,which function should be used? >> It appears your question is which row(s) are contributing most greatly to the overall test of independence. The result of a `chisq.test(.)` (which is not what you see from its print method) has a component named residuals. (Read the help page : ?chisq.test) x2 <- chisq.test(dat) x2$residuals [,1] [,2] [1,] -2.3580463 2.4731398 [2,] 1.4481733 -1.5188569 [3,] 0.9323855 -0.9778942 Those row sums should be distributed as chi-squared statistics with one degree of freedom each, but since you have admittedly inflated the possibility of the type I error, it would be sensible to adjust the "p-statistics" using the function that Jim Lemon misspelled: > rowSums(x2$residuals^2) [1] 11.676803 4.404132 1.825620 > p.adjust( 1- pchisq( rowSums(x2$residuals^2), 1) ) [1] 0.001898526 0.071703921 0.176645786 So row 1 represents the only group that is "significantly different at the conventional level" from the expectations based on the overall sample collection. I also seem to remember that there is a function named CrossTable (in a package whose name I'm forgetting) that will deliver a SAS-style tabulation of row and column chi-squared statistics. -- David. >> >> Many thanks for your help. >> >> My best >> >> >> >> 发自 网易邮箱大师 >>[[alternative HTML version deleted]] >> >> >> __ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] how to perform multiple comparison？
ok,many thanks. 发自 网易邮箱大师 On 2016-05-20 08:19 , Jim Lemon Wrote: Hi laomeng_3, Have a look at the padjust function (stats). Jim On Fri, May 20, 2016 at 1:56 AM, laomeng_3 wrote: > Hi all: > As to the anova, we can perform multiple comparison via TukeyHSD. > But as to chi-square test for frequency table,how to perform multiple > comparison? > > For example, if I want to compare 3 samples' ratio(the data has 3 rows,each > row corresponds to 1 sample,and has 2 columns,each column corresponds to > positive and negative respectively). > > > dat<-matrix(c(6,30,8,23,14,3),nrow=3) > dat > [,1] [,2] > [1,]6 23 > [2,] 30 14 > [3,]83 > > > > chisq.test(dat) > >Pearson's Chi-squared test > > data: dat > X-squared = 17.9066, df = 2, p-value = 0.0001293 > > > The result shows that the difference between the 3 samples is significant.But > if I want to perform multiple comparison to find out which pair of samples is > significantly different,which function should be used? > > > Many thanks for your help. > > My best > > > > 发自 网易邮箱大师 > [[alternative HTML version deleted]] > > > __ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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] how to draw the confidence interval
hi all I have a question about drawing the confidence interval . For instance,if I want to sample 100 times,and each time,the sample size is 10,and the mean and sd is 15 and 1 respectively .I want to draw the 100 confidence intervals(as the attachment) .Which function should be used to draw the confidence interval ? Many thanks! 发自网易邮箱大师 __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] [FORGED] how to draw the confidence interval
this is not homework,just a case which I made by myself. ��ʦ On 2017-03-06 06:47 , Rolf Turner Wrote: On 04/03/17 19:39, laomeng_3 wrote: > hi all I have a question about drawing the confidence interval . > > For instance,if I want to sample 100 times,and each time,the sample > size is 10,and the mean and sd is 15 and 1 respectively .I want to draw > the 100 confidence intervals(as the attachment) .Which function should > be used to draw the confidence interval ? This list does not answer questions about homework. (BTW, no attachment came through; only a *very* limited range of file types is permitted for attachments). cheers, Rolf Turner -- Technical Editor ANZJS Department of Statistics University of Auckland Phone: +64-9-373-7599 ext. 88276 [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
Re: [R] how to draw the confidence interval
thanks a lot. 发自网易邮箱大师 On 2017-03-06 18:19 , Jim Lemon Wrote: Hi laomeng, If you know how to plot the means and calculate the standard deviations, perhaps look at the "dispersion" function in the plotrix package. Jim On Sat, Mar 4, 2017 at 5:39 PM, laomeng_3 wrote: > hi all > I have a question about drawing the confidence interval . > > For instance,if I want to sample 100 times,and each time,the sample size is > 10,and the mean and sd is 15 and 1 respectively .I want to draw the 100 > confidence intervals(as the attachment) .Which function should be used to > draw the confidence interval ? > > Many thanks! > > > > 发自网易邮箱大师 > __ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
