Hi All, I am currently comparing the EEG funcional connectivity measured at 14 electrodes and 4 frequency bands between highly and lowly hypnotic susceptible individuals. I extracted the coherence and the absolute imaginary coherency for all 91 possible connections. As a design for statistical analysis, I chose a two way repeated measures anova. With the within subject variable Condition(no hypnosis, hypnosis) and the between subject variables Group(highly susceptible (7), lowly susceptible (9)) and Connection(different connections between the electrodes(91)).
Unfortunately I am far from meeting the requirements for normality and equality of error variances. Even with ln(x+1), log(x+1), sqrt(x), 1/x transformation.
Does anyone have an idea, which design of non-parametric tests would fit here?
In the foto you can see the structure of my data set for one frequency band.
Any help would be greatly appreciated.
Many thanks.
Dear Andre Filip
The sutabile nonparametric test is friedman test.
There are non-parametric alternatives for your Between x Within design.
You can use an aligned ranks test such as the ARTool. This is a factorial repeated measures ANOVA on the aligned ranks. See: http://depts.washington.edu/ilab/proj/art/index.html
There is also the f1_LD_F1 test which is part of the R package nparLD or the f1_LD_f1 SAS macro. See attachments. Shah & Madden explain and illustrate the method underlying the nparLD method.
Luepsen has also developed an R script art3.anova, which is relevant here.
See: http://www.uni-koeln.de/~luepsen/R/
You could also use the ART R package: https://cran.r-project.org/web/packages/ART/ART.pdf
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