topic Re: How to do exact analysis of s by r table with nominal covariate and ordinal response? in Statistical Procedures

How to do exact analysis of s by r table with nominal covariate and ordinal response?

IsaacNakamura — Mon, 11 Apr 2016 21:23:13 GMT

I use SAS9.4.

I would like to do a exact analysis of s by r table where

the covariate is nominal and the response is ordinal.

Also this is an analysis of categorical data, so we observe the frequency of each covariate*response level.

So the data should look something like

data example;

input covariate $ response $ count @@;

datalines;

cov1 bad 3 cov1 moderate 4 cov1 good 0

cov2 bad 4 cov2 moderate 1 cov2 good 2

cov3 bad 5 cov3 moderate 2 cov3 good 1

;

The sample size is quite small, so I would like to use exact analysis.

I suppose I can do something like

froc freq order=data;

weight count;

tables covariatename*outcomename / exact

run;

But, this should give just a general association, not a "mean score differ" type of result.

What kind of option can I use to do this exact analysis?

Thank you for your help in advance.

Re: How to do exact analysis of s by r table with nominal covariate and ordinal response?

ballardw — Mon, 11 Apr 2016 21:54:44 GMT

To do anything with "difference" I think you need your responses to be numeric. I think you might investigate Proc Npar1way.

proc format library=work;
   invalue response
   'bad' = 1
   'moderate'=2
   'good' =3;
run;
data example;
   informat response response.;
   input covariate $ response  count @@;
datalines;
cov1 bad 3 cov1 moderate 4 cov1 good 0
cov2 bad 4 cov2 moderate 1 cov2 good 2
cov3 bad 5 cov3 moderate 2 cov3 good 1 
;
run;

proc npar1Way data=example;
   class covariate;
   freq count;
   var response;
   exact Wilcoxon;
   
run;

Re: How to do exact analysis of s by r table with nominal covariate and ordinal response?

Ksharp — Tue, 12 Apr 2016 01:31:13 GMT

Friedman’s Chi-Square Test can get "mean score differ" , Check example in Documentation.

proc freq data=Hypnosis;
tables Emotion * SkinResponse /cmh2 scores=rank noprint;

exact ..... ;
run;

OR You could try PROC CATMOD ,which is the best tool to build a Log-Linear Model for Contingency Table.

Re: How to do exact analysis of s by r table with nominal covariate and ordinal response?

IsaacNakamura — Tue, 12 Apr 2016 01:44:38 GMT

Thank you! I will try.

Re: How to do exact analysis of s by r table with nominal covariate and ordinal response?

IsaacNakamura — Tue, 12 Apr 2016 01:44:51 GMT

Thank you. I will try!

Re: How to do exact analysis of s by r table with nominal covariate and ordinal response?

Rick_SAS — Tue, 12 Apr 2016 11:56:58 GMT

For an overview of the various exact tests in PROC FREQ, see "Exact tests in PROC FREQ: What, when, and how."

The PROC FREQ doc says "The Jonckheere-Terpstra test is appropriate for a two-way table in which an ordinal column variable represents the response."

Re: How to do exact analysis of s by r table with nominal covariate and ordinal response?

IsaacNakamura — Thu, 14 Apr 2016 18:54:57 GMT

Thank you! I will try.