Is Dunette's test appropriate for none parametric data?
How valid is SEM foe non parametric data and n=4?
With an N of 4 you will lack enough degrees of freedom to run any kind of statistical analysis.
Hello P.A.,
If your n per group is 4, then you can run paired post hoc tests, but I wouldn't use Dunnett's as it is a special case of a t-test, which implies at least interval strength data. If your data are only ordinal strength, then a test such as the Mann-Whitney U would be an option (comparing two batches at a time), or the Kruskal-Wallis anova by ranks method (for comparing two or more batches at a time) could be used as well. There are numerous ways to adjust the aggregate risk of type I error due to running multiple tests.
However, if the total N = 4, you'll be hard pressed to show differences, even with only two groups, no matter what statistical test you try.
Good luck with your work.
BTW there's no such thing as non paramedic data. There are only nonparametric tests. See a nonparametric statistics textbook. David Booth
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