Below.
> > Usually (but not always) doing tests of normality reflect a lack of > understanding of the power of rank tests, and an assumption of high > power for the tests (qq plots don't always help with that because of > their subjectivity). When possible it's good to choose a > robust method. > Also, doing pre-testing for normality can affect the type I > error of > the overall analysis. > > -- > Frank E Harrell Jr Also, qqplots or any other kind of screening for normality can affect the type I error. Indeed, one might ask what type I error means in such circumstances. :-) Indeed, one might ask what hypothesis testing means in such circumstances. Cheers, Bert ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
