Hi there,

I'm running a logistic regression and put two interaction terms between dummies in the model. The code is like (just put a part of variables in the example):
Code:
logit daily_f feduy ocpfm_dum2 ocpfm_dum3  livewothr_c pintim ///
ocpfm_dum2#livewothr_c ocpfm_dum3#livewothr_c  ///
,or
livewothr_c indicates whether other adult relatives live in the household other than parents (yes or no)
ocpfm_dum2 refers to whether the individual is in a specific category of the occupational status (yes or no)
ocpfm_dum3 is similar to ocpfm_dum2
they are three dummy variables.

Then I ran the command. The results about the interaction terms are:
daily_f | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval]
ocpfm_dum2#livewothr_c |
0 1 | 1.377075 .2156025 2.04 0.041 1.013185 1.871657
1 0 | 1 (omitted)
1 1 | 1 (omitted)
|
livewothr_c#ocpfm_dum3 |
0 1 | 1.967462 .4669052 2.85 0.004 1.235677 3.132622
1 0 | 1 (omitted)
1 1 | 1 (omitted)
|
I'm confused about why 1 0 and 1 1 are omitted.Should I check the data? Or the command is wrong? Or it is normal but I did not understand it?

Thank you so much.