Question 9: What other approaches could be used?
We could use a sign test, as described in topic 3, significance tests.
We could also consider a method based on rank order, the Wilcoxon paired sample test. This is not covered in this module. It is what Doug Altman suggests in his book, whence this exercise comes, but I think that the assumption it requires, that the distribution of the differences should be symmetrical, is not met by these data.
Back to Exercise: Transformations.
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Last updated: 27 July, 2009.