Programming the statistical procedures from SAS

Relationship between categorical variables

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Contributor
Posts: 27

Relationship between categorical variables

Hello, 

 

I am not sure if I should post this here as this technically isn't a SAS question..(but somewhat related). I have about 180 subjects in my dataset, and primarily interested in examining the relationship between three modifiable behavioral factors (two binary and one three-level nominal) that could be potentially associated with the outcome (death; all 180 subjects). Because the data wasn't collected for research per se, I do not have a reference or a control group to compare. My question is: is there any statistical analyses I can do to examine the relationship between these three modifiable risk factor variables? I tried chi-sq and it was helpful, but I am curious to find out if there are other tests I could perform. Can tetrchoric or polychoric (PROC FREQ) corr or performing factor analyses (using the matrix from the correlation procedure) be meaninful in any way?  

 

 

Thank you!

 

 

SAS Super FREQ
Posts: 3,547

Re: Relationship between categorical variables

In addition to tests for association in PROC FREQ, you might look at correspondence analysis, which is the discrete/categorical analogue of principal component analysis.  In SAS, you can carry out correspondence analysis by using the CORREP procedure.  

Contributor
Posts: 27

Re: Relationship between categorical variables

I see. I didn't know about correspondence analysis, so I appreciate the suggestion! Does this mean the statistics I got from PLCORR such as Tetrachoric values (in PROC FREQ) are not valid?
SAS Super FREQ
Posts: 3,547

Re: Relationship between categorical variables

?? I don't see why they wouldn't be valid.  Correspondence analysis is a multivariate technique that attempts to reveal relationships in categorical variables. But it doesn't replace or invalidate other statistical methods.

Contributor
Posts: 27

Re: Relationship between categorical variables

Oh ok. I said that not because you suggested a different method, but I read somewhere that standard methods of performing FA (using a tetra/polychoric correlations matrix) assume that factors are continuous. I also noticed that having a three-level nominal var in the matrix generate some funky numbers (compared to only having binary vars).

Thanks again for the suggestion!
Super User
Posts: 10,871

Re: Relationship between categorical variables

Logistic regression is a common way of examining data with two outcomes (it looks like death/alive in your case?) with one or more factors that are typically not continuous such as  smoker/nonsmoker, low/middle/high value indicator, gender or such.

Contributor
Posts: 27

Re: Relationship between categorical variables

Hello,
Unfortunately, I only have one outcome (death) otherwise I would have totally tried logistic reg!
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