Hi: It strikes me as a little curious that the No Virus values in each of your example data sets are all *exactly* 1. Why is that?
Dennis On Thu, Apr 29, 2010 at 4:52 AM, Yanwei Tan <t...@nbio.uni-heidelberg.de>wrote: > Dear all, > > I have a quite basic questions about anova analysis in R, sorry for this, > but I have no clue how to explain this result. > > I have two datasets which are named: nmda123, nmda456. Each dataset has > three samples which were measured three times. And I would like to compare > means of them with Posthoc test using R, following please see the output: > > (CREB, mCREB and No virus are the name of samples) > > > nmda123 > Values ind > 1 6.7171265 CREB > 2 5.0343117 CREB > 3 6.9000000 CREB > 4 0.1195394 mCREB > 5 0.1221876 mCREB > 6 0.1900000 mCREB > 7 1.0000000 No Virus > 8 1.0000000 No Virus > 9 1.0000000 No Virus > > > nmda456 > Values ind > 1 6.4486940 CREB > 2 6.2277490 CREB > 3 6.5000000 CREB > 4 0.2000000 mCREB > 5 0.3766052 mCREB > 6 0.4000000 mCREB > 7 1.0000000 No Virus > 8 1.0000000 No Virus > 9 1.0000000 No Virus > > > TukeyHSD(aov(Values ~ ind, data = nmda456)) > Tukey multiple comparisons of means > 95% family-wise confidence level > > Fit: aov(formula = Values ~ ind, data = nmda456) > > $ind > diff lwr upr p adj > mCREB-CREB -6.0666126 -6.3289033 -5.8043219 0.0000000 > No Virus-CREB -5.3921477 -5.6544383 -5.1298570 0.0000000 > No Virus-mCREB 0.6744649 0.4121743 0.9367556 0.0005382 > > > TukeyHSD(aov(Values ~ ind, data = nmda123)) > Tukey multiple comparisons of means > 95% family-wise confidence level > > Fit: aov(formula = Values ~ ind, data = nmda123) > > $ind > diff lwr upr p adj > mCREB-CREB -6.073237 -7.5618886 -4.584585 0.0000392 > No Virus-CREB -5.217146 -6.7057976 -3.728495 0.0000943 > No Virus-mCREB 0.856091 -0.6325606 2.344743 0.2588450 > > So my question is No virus-mCREB group. Even I looked at the data by eyes, > there is big difference between no virus and mCREB in data nmda123, but why > the pvalue is 0.2588450, but in nmda456 data, the pvalue is 0.0005382. But > I can see there is bigger difference in nmda123 than nmda456, I do not know > why. Sorry for my inexperiences in statistics. > > Thanks for your reply and time! > > Cheers, > Wei > > ______________________________________________ > 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. > [[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.
