Short rep: I have two distributions, data and data2; each build from about 3 million data points; they appear similar when looking at densities and histograms. I plotted qqplots for further eye-balling:
qqplot(data, data2, xlab = "1", ylab = "2") and get an almost perfect diagonal line which means they are in fact very alike. Now I tried to check normality using qqnorm -- and I think I am doing something wrong here: qqnorm(data, main = "Q-Q normality plot for 1") qqnorm(data2, main = "Q-Q normality plot for 2") I am getting perfect S-shaped curves (??) for both distributions. Am I something missing here? | | * * * * | * | * | * | * | * | * | * * * |--------------------------------------------- Thanks, Ralf On Thu, Jun 24, 2010 at 8:23 PM, Ralf B <ralf.bie...@gmail.com> wrote: > Unfortunately not. I want a qqplot from two variables. > > Ralf > > > On Thu, Jun 24, 2010 at 7:23 PM, Joris Meys <jorism...@gmail.com> wrote: >> Also take a look at qq.plot in the package "car". Gives you exactly >> what you want. >> Cheers >> Joris >> >> On Fri, Jun 25, 2010 at 12:55 AM, Ralf B <ralf.bie...@gmail.com> wrote: >>> More details... >>> >>> I have two distributions which are very similar. I have plotted >>> density plots already from the two distributions. In addition, >>> I created a qqplot that show an almost straight line. What I want is a >>> line that represents the ideal case in which the two >>> distributions match perfectly. I would use this line to see how much >>> the errors divert at different stages of the plot. >>> >>> Ralf >>> >>> >>> >>> On Thu, Jun 24, 2010 at 5:56 PM, stephen sefick <ssef...@gmail.com> wrote: >>>> You are going to have to define the question a little better. Also, >>>> please provide a reproducible example. >>>> >>>> On Thu, Jun 24, 2010 at 4:44 PM, Ralf B <ralf.bie...@gmail.com> wrote: >>>>> I am a beginner in R, so please don't step on me if this is too >>>>> simple. I have two data sets datax and datay for which I created a >>>>> qqplot >>>>> >>>>> qqplot(datax,datay) >>>>> >>>>> but now I want a line that indicates the perfect match so that I can >>>>> see how much the plot diverts from the ideal. This ideal however is >>>>> not normal, so I think qqnorm and qqline cannot be applied. >>>>> >>>>> Perhaps you can help? >>>>> >>>>> Ralf >>>>> >>>>> ______________________________________________ >>>>> 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. >>>>> >>>> >>>> >>>> >>>> -- >>>> Stephen Sefick >>>> ____________________________________ >>>> | Auburn University | >>>> | Department of Biological Sciences | >>>> | 331 Funchess Hall | >>>> | Auburn, Alabama | >>>> | 36849 | >>>> |___________________________________| >>>> | sas0...@auburn.edu | >>>> | http://www.auburn.edu/~sas0025 | >>>> |___________________________________| >>>> >>>> Let's not spend our time and resources thinking about things that are >>>> so little or so large that all they really do for us is puff us up and >>>> make us feel like gods. We are mammals, and have not exhausted the >>>> annoying little problems of being mammals. >>>> >>>> -K. Mullis >>>> >>> >>> ______________________________________________ >>> 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. >>> >> >> >> >> -- >> Joris Meys >> Statistical consultant >> >> Ghent University >> Faculty of Bioscience Engineering >> Department of Applied mathematics, biometrics and process control >> >> tel : +32 9 264 59 87 >> joris.m...@ugent.be >> ------------------------------- >> Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php >> > ______________________________________________ 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.
