Re: [R] ordinal variables

From: Joris Meys <>
Date: Thu, 03 Jun 2010 15:35:14 +0200

see ?factor and ?as.factor. On ordered factors you can technically do a spearman without problem, apart from the fact that a spearman test by definition cannot give exact p-values with ties present.

x <- sample(c("a","b","c","d","e"),100,replace=T) y <- sample(c("a","b","c","d","e"),100,replace=T)

x.ordered <- factor(x,levels=c("e","b","a","d","c"),ordered=T)
y.ordered <- factor(y,levels=c("e","b","a","d","c"),ordered=T)



R commander has some menu options to deal with factors. R commander also provides a scripting window. Please do your students a favor, and show them how to use those commands.


On Thu, Jun 3, 2010 at 2:25 PM, Iasonas Lamprianou <>wrote:

> Dear colleagues,
> I teach statistics using SPSS. I want to use R instead. I hit on one
> problem and I need some quick advice. When I want to work with ordinal
> variables, in SPSS I can compute the median or create a barchart or compute
> a spearman correlation with no problems. In R, if I "read" the ordinal
> variable as numeric, then I cannot do a barplot because I miss the category
> names. If I read the variables as characters, then I cannot run a spearman.
> How can I read a variable as numeric, still have the chance to assign value
> labels, and be able to get table of frequencies etc? I want to be able to do
> all these things in R commander. My students will probable be scared away if
> I try anything else other than R commander (just writing commands will not
> make them happy).
> I hope I am not asking for too much. Hopefully there is a way
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.

Joris Meys
Statistical Consultant

Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

Coupure Links 653
B-9000 Gent

tel : +32 9 264 59 87
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Received on Thu 03 Jun 2010 - 13:37:34 GMT

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