topic Re: Odds ratios by stratum in Proc freq in SAS Procedures

Odds ratios by stratum in Proc freq

Jaime2 — Mon, 07 Oct 2019 20:45:13 GMT

I'm doing differential item functioning (DIF) analyses using the CMH in Proc Freq and based on the breslow-day test of

Homogeneity of the Odds Ratios, there appears to be some nonuniform DIF. My question is whether I can use a keyword to request that the odds ratios be saved/printed for each of my 10 strata.

I've looked on the SAS 9.3 documentation for this proc and can't find any related information.

I'm using SAS 9.4

Re: Odds ratios by stratum in Proc freq

ballardw — Mon, 07 Oct 2019 20:48:37 GMT

@Jaime2 wrote:

I'm doing differential item functioning (DIF) analyses using the CMH in Proc Freq and based on the breslow-day test of

Homogeneity of the Odds Ratios, there appears to be some nonuniform DIF. My question is whether I can use a keyword to request that the odds ratios be saved/printed for each of my 10 strata.

I've looked on the SAS 9.3 documentation for this proc and can't find any related information.

I'm using SAS 9.4

It would help to show the code you are currently running. Some of the options to create output data sets, which is how I interpret "saved" require knowing which options were used to create the output. The OUTPUT statement may suffice or likely ODS OUTPUT.

Re: Odds ratios by stratum in Proc freq

Reeza — Mon, 07 Oct 2019 20:55:41 GMT

Here's some instructions and explanations on how to capture output that is shown.
https://blogs.sas.com/content/sastraining/2017/03/31/capturing-output-from-any-procedure-with-an-ods-output-statement/

If the output is shown you can capture it with the method above.

Re: Odds ratios by stratum in Proc freq

Jaime2 — Mon, 07 Oct 2019 21:01:03 GMT

Hi, Thanks for your reply - 'CMH' is the only option I have in the tables statement. I don't see any odds ratios for the individual strata, only the general odds ratio.

proc freq data =mydata;

tables stratum*mode*item&i./ CMH ;

Re: Odds ratios by stratum in Proc freq

Jaime2 — Mon, 07 Oct 2019 21:03:30 GMT

Thank you for this link! My problem is the OR is not there to begin with

Re: Odds ratios by stratum in Proc freq

Reeza — Mon, 07 Oct 2019 21:16:04 GMT

I think odds ratio are only done for 2x2 tables. You may need to use PROC LOGISTIC to get the odds ratio.

Re: Odds ratios by stratum in Proc freq

Watts — Mon, 07 Oct 2019 21:30:23 GMT

For stratified 2x2 tables, the CMH provides the overall odds ratios and the Breslow-Day test. The OR option displays the stratum-level odds ratios.

Re: Odds ratios by stratum in Proc freq

Jaime2 — Mon, 07 Oct 2019 21:42:22 GMT

Thanks so much. For some reason I was stuck on trying to get the MH odds ratio for each stratum - but this works.