[R] friedman.test error: not an unreplicated complete block design

[lindsay hanford]

Hello R Community,

I am using the friedman.test() function to test differences in a non-normally
distributed dataset, with a dependent variable that either a
continuous variable or a ratio and has 2+ groups.

I am using the friedman.test instead of a repeated measures ANOVA because
my dataset violated the assumptions for using an ANOVA. I am looking to
compare response means on an emotion-labelling task, between groups (HR,
HC) and emotions (Happy, Sad, Angry, Fearful) where these variables are my
group and block variables, respectively.

When I use the following command:
> friedman.test(Response~Group|Emotion, data=dataset)
I get the following error:
Error in friedman.test.default(c(1L, 1L, 0L, 0L, 0L, 1L, 0L, 2L, 0L, 0L, :
not an unreplicated complete block design

I believe I have set up my dataset correctly.. where Subject ID is repeated for
the four categories of emotion. The variable Error contains the number of
incorrect response corresponding to each emotion.


*Subj Group Emotion Response*94 HR Happy 2
119 HC Happy 0
....
3 HR Sad 4
61 HC Sad 2
64 HC Sad 0
....etc

I think the error c(1L, 1L, 0L, 0L, 0L, 1L, 0L, 2L, 0L, 0L,... ) corresponds
to my Response variable and might not be happy about is the number of 0's that
appear in that variable. However, this is the reason my dataset is not normally
distributed and I cannot use rmANOVA.

Any ideas how to deal with this error? Or whether I should be using a
different statistical test?
Thanks,

Lindsay
--
Lindsay Hanford, BSc, PhD Candidate
McMaster Integrative Neuroscience Discovery & Study | *Department of
Psychology, Neuroscience & Behaviour *
McMaster University *|* lindsay...@gmail.com

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[John Kane]

We really need " commented, minimal, self-contained, reproducible code' as asked for in the note at the end of each R-help message.

Have a look at http://adv-r.had.co.nz/Reproducibility.html and/or http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example for some hints.

In particular, in your case we almost certainly need some data. Please use dput() to produce a useable data set. See Hakley's discussion at http://adv-r.had.co.nz/Reproducibility.html for an example of how to to this.
John Kane
Kingston ON Canada

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[Michael Dewey]

Dear Lindsay
If the problem is that you have an excess of zeroes you might look at
the vignette for the package pscl which is called something like
Regression models for count data.

Michael
http://www.dewey.myzen.co.uk/home.html

[peter dalgaard]

By coincidence, there actually _is_ enough info to pinpoint the issue:

*Subj Group Emotion Response*94 HR Happy 2
119 HC Happy 0
....
3 HR Sad 4
61 HC Sad 2
64 HC Sad 0
....etc

An unreplicated complete block design has exactly 1 observation for each combination of the two grouping factors. The above clearly has 2 observations with "HC, Sad". So Friedman's test does not apply.

--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: PDa...@gmail.com

[lindsay hanford]

Hi Peter,

I thought it was possible to have multiple subjects in each group, while
still specifying another factor, as is the case for repeated measures
ANOVA. If this is not the case, I guess I should look into Regression
models for count data as suggested by Micheal.

McMaster University *|* 1280 Main Street West, PC329 Psychology Building *|*
Hamilton, ON, L8S 4L8
905 525 9140 x24784 *|* lindsay...@gmail.com