... Moreover, you should not analyze proportions in this way, which treats .5 = 2/4 or .5 = 2000/4000 identically. As David said, you need to work with a statistician.
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 Sat, Dec 22, 2018 at 7:32 AM David L Carlson <dcarl...@tamu.edu> wrote: > You may need to spend some more time with the statistician who needs to > see your data. It is not clear if you have a two sample test or a paired > sample test. Kruskall-Wallis expects data for each observation, not grouped > data. Without the observations, the test cannot compute the sample size and > the degrees of freedom. You have run kruskal.test separately on each > sample. The kruskal.test is designed for comparing two or more samples. > > ---------------------------------------- > David L Carlson > Department of Anthropology > Texas A&M University > College Station, TX 77843-4352 > > -----Original Message----- > From: R-help <r-help-boun...@r-project.org> On Behalf Of Jenny Liu > Sent: Saturday, December 22, 2018 7:10 AM > To: Michael Dewey <li...@dewey.myzen.co.uk> > Cc: r-help@r-project.org > Subject: Re: [R] Glitch in Kruskal-Wallis test? > > Hi Michael, > > Thank you for your reply! I'm testing the difference in proportions. Temp > is temperature, and Prop is the proportion of insect pupae that survived at > that temperature. I was told by a statistician that the K-W was appropriate > for testing proportions, but perhaps you know of an alternative? I have > already tested for heteroscedasticity using the Breusch-Pagan test. > > Thanks again, > Jenny > > > > On Dec 22, 2018 7:38 AM, "Michael Dewey" <li...@dewey.myzen.co.uk> wrote: > > Dear Jenny > > What exactly do you think you are testing here? You are telling K-W you > have seven groups each with a single value which is not the usual > situation for K-W. > > Michael > > > On 22/12/2018 04:58, Jenny Liu wrote: > > Hi everyone, > > I have been running a K-W test with the attached data, PupMort1. My code: > > kruskal.test(Prop~Temp,data=PupMort1) > > However, I found that I get the exact same result when I change the > x-values, as > > in the attached data PupMort2. > > Test run with PupMort1Kruskal-Wallis rank sum testdata: Prop by Temp > > > Kruskal-Wallis chi-squared = 6, df = 6, p-value = 0.4232 > > Test run with PupMort2Kruskal-Wallis rank sum testdata: Prop by Temp > > > Kruskal-Wallis chi-squared = 6, df = 6, p-value = 0.4232 > > Does anybody know why this is happening? > > Thank you! > > Jenny > > > > > > ______________________________________________ > > 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. > > > > -- > Michael > http://www.dewey.myzen.co.uk/home.html > > [[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. > [[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.
