#same shape some_data <- rgamma(500,shape=6,scale=2) test_data <- rgamma(500,shape=6,scale=2) plot(sort(some_data),sort(test_data)) # You can also use qqplot(some_data,test_data) abline(0,1)
# different shape some_data <- rgamma(500,shape=6,scale=2) test_data <- rgamma(500,shape=4,scale=2) plot(sort(some_data),sort(test_data)) abline(0,1) It is helpful to assess the sampling variability, by creating repeated sets of test_data, and plotting all of these along with your observations to create a confidence "envelope". The SuppDists provides Inverse Gauss. On Thu, Sep 17, 2009 at 11:46 AM, Petar Milin <pmi...@ff.uns.ac.rs> wrote: > Hello! > I am trying with this question again: > I would like to test few distributional assumptions for some behavioral > response data. There are few theories about true distribution of those data, > like: normal, lognormal, gamma, ex-Gaussian (exponential-Gaussian), Wald > (inverse Gaussian) etc. The best way would be via qq-plot, to show to > students differences. First two are trivial: > qqnorm(dat$X) > qqnorm(log(dat$X)) > Then, things are getting more "hairy". I am not sure how to make plots for > the rest. I tried gamma with: > qqmath(~ X, data=dat, distribution=function(X) > qgamma(X, shape, scale)) > Which should be the same as: > plot(qgamma(ppoints(dat$X), shape, scale), sort(dat$X)) > Shape and scale parameters I got via mhsmm package that has gammafit() for > shape and scale parameters estimation. > Am I on right track? Does anyone know how to plot the rest: ex-Gaussian > (exponential-Gaussian), Wald (inverse Gaussian)? > > Thanks, > PM > > ______________________________________________ > 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<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.
