Friedman Test
Hello,
I am trying to conduct a Friedman test for my data (2 independent groups, n1 = 13, n2 = 17). I am getting the error message "Not an unreplicated complete block design" when trying to run the Friedman test (through Repeated Measures ANOVA -> Nonparametrics).
Based on the error message, I'd assume it has to do with the different sample sizes? As far as I know, the Friedman test doesn't require the same sample sizes for both groups; am I wrong?
Thank you in advance!
Comments
I forgot to add: In both groups there is one participant with missing data.
Hi @MaximusLuminis ,
I'm afraid that's a limitation of the Friedman test - it requires complete observations (e.g., see here), so you can only run it for those participants who completed all trials.
Do you also have a within subjects measurement? Because in your description you only mention the independent groups.
Kind regards,
Johnny
Hi @JohnnyB ,
thanks for the reply! Wouldn't it be possible to automatically exclude the participants with missing data? I think that would be a better solution than simply "refusing" to calculate the test.
Yes, we have three within-subject measurements (the two independent groups did some cognitive tests and questionnaires at three time points).
Kind regards,
Maximus
Hi @MaximusLuminis ,
In that case it will be a bit tricky, because the Friedman test is generally for one-way RM ANOVA's, not for multiple repeated measures. One option to explore would be to try a rank-transformed ANOVA, where you convert your DV to their ranks, and then run the RM ANOVA (although see the warnings here: https://en.wikipedia.org/wiki/ANOVA_on_ranks)
Cheers
Johnny
You could consider imputing the missing value?