Interaction Between a Dummy Variable and a Continuous Variable?

[Thalia Tran]

Hello
I am newbie to Stata and Statistic.
I have run the interaction term only in my stata
ologit Bribe i.Rela#c.Anti $cov
To the best of my knowledge, there has to be a reference group (ex Rela1) and this category cannot show up in the result table. But it is still there.
When I run ologit Bribe i.Rela_ref $cov, the Rela1 was reference one and didnt show up. How can I understand the coeffiecent of the former case?
Thank you

ologit Bribe i.Rela $cov

[Carlo Lazzaro]

Thalia:
welocme to this forum.
The best way to investigate this issue is to take a look at the coefficient matrix:

. use "C:\Program Files\Stata18\ado\base\a\auto.dta"
(1978 automobile data)

. ologit rep78 i.foreign##c.mpg

Iteration 0:  Log likelihood = -93.692061  
Iteration 1:  Log likelihood = -79.023882  
Iteration 2:  Log likelihood = -78.095359  
Iteration 3:  Log likelihood = -78.071936  
Iteration 4:  Log likelihood = -78.071908  
Iteration 5:  Log likelihood = -78.071908  

Ordered logistic regression                             Number of obs =     69
                                                        LR chi2(3)    =  31.24
                                                        Prob > chi2   = 0.0000
Log likelihood = -78.071908                             Pseudo R2     = 0.1667

-------------------------------------------------------------------------------
        rep78 | Coefficient  Std. err.      z    P>|z|     [95% conf. interval]
--------------+----------------------------------------------------------------
      foreign |
     Foreign  |   3.015042   2.328281     1.29   0.195    -1.548304    7.578389
          mpg |   .0755395   .0662507     1.14   0.254    -.0543095    .2053886
              |
foreign#c.mpg |
     Foreign  |  -.0183244   .0981388    -0.19   0.852    -.2106729    .1740241
--------------+----------------------------------------------------------------
        /cut1 |  -1.730257   1.435715                     -4.544206    1.083693
        /cut2 |   .0627867   1.291372                     -2.468255    2.593829
        /cut3 |   2.685685   1.338266                      .0627317    5.308638
        /cut4 |   4.741767   1.436722                      1.925843     7.55769
-------------------------------------------------------------------------------

. mat list e(b)

e(b)[1,9]
          rep78:       rep78:       rep78:       rep78:       rep78:           /:           /:           /:           /:
             0b.           1.               0b.foreign#   1.foreign#                                                    
        foreign      foreign          mpg       co.mpg        c.mpg         cut1         cut2         cut3         cut4
y1            0    3.0150423    .07553953            0   -.01832441   -1.7302568    .06278669    2.6856848    4.7417665

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