Re: Percent Change Crosstabs

Posted by Bruce Weaver on May 29, 2013; 8:32pm
URL: http://spssx-discussion.165.s1.nabble.com/Percent-Change-Crosstabs-tp5720440p5720471.html

Thanks Gene.  For completeness, the reciprocal of the absolute risk reduction (at least in studies involving treatment vs control) is called the "number needed to treat" (NNT).  Clinicians seem to like it as a measure of effect.  It tells them how many patients they need to treat in order for one to benefit.  There is also number needed to harm (NNH) if one is talking about unwanted side effects, for example.

@Rich -- I agree that the thread probably did become more complicated than necessary if the situation is limited to 2x2 tables.  It's my fault it got that complicated.  My excuse (if you will) is that I was pretty certain the OP wanted the risk difference with its CI, and they won't get that (at least not easily) from CROSSTABS output.  

@Jon -- Is there any possibility (in a future release) of having the risk difference (and maybe NNT) added to the output one gets when including RISK on the STATISTICS sub-command?  That would be quite useful, I think.

Cheers,
Bruce

Maguin, Eugene wrote

I enjoyed this discussion because I learned about risk difference and risk ratio, neither of which I'd heard of before. So, thanks to Bruce, Ryan, and Rich.

Gene Maguin