Hello,

I am trying to assess for interaction where the primary association is estrogen use and endometrial cancer. I have not been successful in trouble shooting and receive the same errors when the i.'s and c.'s are left out and also when I use two #'s in the interaction terms. Is the output due an error in my code and, if so, could someone please recommend a method for troubleshooting? Please see below for the code and the errors.

Thank you!


When I input the following code:
clogit case est c.age gall ob non hyp i.dose c.dur i.est#c.age i.est#i.gall i.est#i.ob i.est#i.non i.est#i.hyp i.est#i.dose i.est#c.dur, group(set) or

I receive these errors:

note: 1.est#1.gall omitted because of collinearity
note: 1.est#1.ob omitted because of collinearity
note: 1.est#1.non omitted because of collinearity
note: 1.est#0.hyp omitted because of collinearity
note: 1.est#1.hyp omitted because of collinearity
note: 0.est#1.dose identifies no observations in the sample
note: 0.est#2.dose identifies no observations in the sample
note: 0.est#3.dose identifies no observations in the sample
note: 0.est#4.dose identifies no observations in the sample
note: 0.est#5.dose identifies no observations in the sample
note: 0.est#6.dose identifies no observations in the sample
note: 1.est#0.dose omitted because of collinearity
note: 1.est#1.dose omitted because of collinearity
note: 1.est#2.dose omitted because of collinearity
note: 1.est#3.dose omitted because of collinearity
note: 1.est#4.dose omitted because of collinearity
note: 1.est#5.dose omitted because of collinearity
note: 1.est#6.dose omitted because of collinearity
note: 1.est#c.dur omitted because of collinearity
note: 17 groups (17 obs) dropped because of all positive or
all negative outcomes.