Dear Statalist,
Actually, I am bit confused between the joint effect and the moderating impact. I mean I saw some people doing the following example:

Cancer = Smoker + Sport + Smoker*Sport.

So the code in STATA will be if am using panel data:

Code:
Xtologit Cancer i.Smoker##i.Sport
So, I believe the above is the joint effect.

But, what if I want to see the moderating impact of Sport on the relationship between Cancer and Smoker. How the model should look like and what is the code for this by using the above variables?

Many thanks in advance.