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Friedman test on JMP?

beginners_luck

Dear all,

I am fairly new in using the JMP software, and as far as I can see there is no function in the programme for using the Friedman test? I have a non-normal distribution of my different sets of values (more than three groups) and is opting for a non-parametric test. That is, I had like to test a 2-way type of test (as ANOVA). Wilcoxon test is insufficient since it is a one-way test.

Do anybody know how I will deal with is problem? Is there another test to perform instead of Friedman test?

Best regards,

Accepted answers

Jeff_Perkinson

Hi Jim,

Friedman's test is not supported directly in JMP but, as Steve points out you can do this by calculating the ranks within each block and then doing a two way ANOVA on ranks using Fit Y by X (treating one of the effects as a blocking variable).

Computing the ranks within block is easy in JMP. Just use the Distribution platform with your original response as Y and your blocking variable as a By variable. Then, in the resulting report, hold down the Ctrl key and click on the little red triangle at the top of one of the histograms and choose Save->Ranks. You'll get a new column in your data table with the ranks within levels of your blocking variable.

I hope that helps!

-Jeff

All comments

stevedenham

If you can't find the Friedman test in the menus (and I have no idea whether you can or not, since I am not a JMP user), you could rank transform your data, and use a two-way ANOVA on the ranks. In SAS, this is available in PROC FREQ, so I would check the JMP documentation for the possibility of doing Friedman's test in that manner.

Steve Denham

beginners_luck

Thanks for the help. Although the Friedman test seem not listed in the JMP menu or elsewhere in the programme. Perhaps I need to perform it on SAS if JMP doesnt conduct these tests.

Best regards,

Jim

Jeff_Perkinson

Hi Jim,

I hope that helps!

-Jeff

beginners_luck

Thank you very much Jeff. However I am not sure I have found what I am looking for: 2-way ANOVA. It seem in the end I receive only one-way ANOVA data in the output file. This is what I did: First, I conducted Distribution analyses and rank transformed data from one of the traits I have studied (Y) accoridng to its randomized block design, i.e. block (By). The data was saved as ranks (six rank/block data compiled into one column of the Jmp data sheet), and next I analyzed the rank transformed trait with Fit Y by X: Y as rank data, and for X I used treatment as a variable. However, in the output file I only see one-way ANOVA data!

Have it been conducted the wrong way? Or is the data to be find somewhewre within the output file?

Thankful for input in this matter!

Best regards,

Jim

34South

I realise this is an old discussion, but I found it most helpful. I have been able to successfully implement it but have the following question:

For evaluating the impact of both variables on the outcome variable, I assume one must test each separately, using ranks created using both but alternating them between blocking and dependent roles. However, how does one determine interaction between these two variables? Luckily I was able to transform my data successfully and perform a two way ANOVA using the Fit Model platform. Is this a limitation of the Friedman test?