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 -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: PupMort1.txt URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20181222/10ab57ac/attachment.txt> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: PupMort2.txt URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20181222/10ab57ac/attachment-0001.txt>
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 at 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
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" <lists at 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 thex-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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guidehttp://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]]