How do I print glm coefficients for all factor levels, including reference level? summary(glm_obj) prints only the values that deviate from reference values.
I know that those are 0's, but I need this for integration, i.e. telling other systems what factor levels can happen at all.
Sorry if it's too simple, could not find anywhere.
Thanks
To illustrate the problem I am facing:
> glm(Petal.Width~Species,data=iris)  
Call:  glm(formula = Petal.Width ~ Species, data = iris)  
Coefficients:
          (Intercept)  Speciesversicolor   Speciesvirginica  
                0.246              1.080              1.780  
Degrees of Freedom: 149 Total (i.e. Null);  147 Residual
Null Deviance:      86.57 
Residual Deviance: 6.157    AIC: -45.29`
The model description above yields only coefficients for versicolor and virginica, which is, as Dason has noted, absolutely fine from the point of view of the model itself.
However, I needed to share the model with another application, which must know what levels of Species to expect (and e.g. issue a warning in once a new, unstudied level appears).
Summary() gives the same results:
> summary(glm(Petal.Width~Species,data=iris))
Call:
glm(formula = Petal.Width ~ Species, data = iris)
Deviance Residuals: 
   Min      1Q  Median      3Q     Max  
-0.626  -0.126  -0.026   0.154   0.474  
Coefficients:
                  Estimate Std. Error t value Pr(>|t|)    
(Intercept)        0.24600    0.02894    8.50 1.96e-14 ***
Speciesversicolor  1.08000    0.04093   26.39  < 2e-16 ***
Speciesvirginica   1.78000    0.04093   43.49  < 2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
(Dispersion parameter for gaussian family taken to be 0.04188163)
Null deviance: 86.5699  on 149  degrees of freedom
Residual deviance:  6.1566  on 147  degrees of freedom
AIC: -45.285
Number of Fisher Scoring iterations: 2
So I realise this question is pretty old, but a simple solution is to use the dummy.coef function
fit<-glm(Petal.Width~Species,data=iris)  
summary(fit)
dummy.coef(fit)
> dummy.coef(fit)
Full coefficients are 
(Intercept):     0.246                     
Species:        setosa versicolor virginica
                  0.00       1.08      1.78
I hope this helps!
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