Dear All I am trying to study four-way interactions in an ANOVA problem. However, qqnorm+qqline result
(at http://phhs80.googlepages.com/qqnorm.png) is not promising regarding the normality of data (960 observations). The result of Shapiro-Wilk test is also not encouraging: W = 0.9174, p-value < 2.2e-16 (I am aware of the fact that normality tests tend to reject normality for large samples.) By the way, the histogram is at: http://phhs80.googlepages.com/hist.png To circumvent the problem, I looked for non-parametric tests, but I found nothing, but the article: http://www.pgia.ac.lk/socs/asasl/journal_papers/PDFformat/g.bakeerathanpaper-2.pdf Finally, my question is: has R got implemented functions to use non-parametric tests to avoid the fulfillment of the normality assumption required to study four-way interactions? Thanks in advance, Paul ______________________________________________ [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 and provide commented, minimal, self-contained, reproducible code.
