proc logistic - odds ratio for interaction terms

[ChuksManuel]

Hello guys, i am a little confused and a simple explanation will help here. 

I ran these two codes. The second code is for the interaction model.

Variable names are "mi" and "sprob"

Proc logistic data = new descending; Model health = mi sprob; run;

Proc logistic data = new descending; Model health = mi sprob mi*sprob ; run;

I discovered that the Odds ratios was not displayed  for 'mi' or 'sprob' in the interaction model  when i ran it and i am wondering the reason why. The first code gave me an odds ratio but the second just didn't. Is there any theory for this? Either statistical or otherwise?

Thanks

[StatDave · Accepted solution]

See this note.