[R] Non-parametric four-way interactions?
Paul Smith
phhs80 at gmail.com
Thu Jul 27 03:49:51 CEST 2006
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
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