If you ran both the SAS Survey and SUDAAN programs (or reviewed the output provided on the Sample Code and Datasets Page page), you may have noticed slight differences in the output. These differences can be caused by missing data in any paired PSU or how each software program handles degrees of freedom.

- Both programs calculate that 1,304 respondents have hypertension and 2,515 do not.
- The beta coefficient and odds ratio estimates are identical.
- The variance estimates and standard errors are identical if there are no missing data in any paired PSUs (which was the case in this example). They will be different if any one of the paired PSUs contains missing data, as SAS and SUDAAN handle stratum contribution from the missing cells differently.
- The confidence intervals are slightly different since SAS and SUDAAN handles degrees of freedom differently.

- Watch animation of output comparison
- Can't view the demonstration? Try our Tech Tips for troubleshooting help.