How does factor works in R-glm

@miotot wrote:

Hi Gurus,

As I am new to this tool and data analytics in general, just want to understand how the factors work in R (or probably in more general sense).
For example, I have this set of data

"indicator"	"countrycode"	"distance"
0	US	0.1
0	US	0.18
0	US	0.21
0	US	0.19
1	US	0.2
1	US	0.21
0	GB	0.24
0	GB	0.23
0	GB	0.21
0	GB	0.22
1	GB	0.2
1	FR	0.1

and want to perform logistics regression model to predict the indicator.
myFullLRModel = glm(indicator ~ countrycode + distance, data=myraw.data, family=binomial)

So I got the result (as below) which it excludes the value for FR which I have expected.

Call:
glm(formula = indicator ~ countrycode + distance, family = binomial,
    data = myraw.data)

Deviance Residuals:
    Min       1Q   Median       3Q      Max
-1.0474  -0.7889  -0.6405   0.3285   1.9414

Coefficients:
              Estimate Std. Error z value Pr(>|z|)
(Intercept)      15.97    3956.18   0.004    0.997
countrycodeGB   -20.88    3956.18  -0.005    0.996
countrycodeUS   -19.63    3956.18  -0.005    0.996
distance         15.92      28.81   0.552    0.581

(Dispersion parameter for binomial family taken to be 1)

    Null deviance: 15.276  on 11  degrees of freedom
Residual deviance: 12.256  on  8  degrees of freedom
AIC: 20.256

Number of Fisher Scoring iterations: 16

Now my question is, when I interchanged the values of the country from GB to FR and/or FR to GB, I expected that it will exclude the coefficients for GB, and it will show coefficients for country code “FR”. But results shows differently (as per below)

"indicator"	"countrycode"	"distance"
0	US	0.1
0	US	0.18
0	US	0.21
0	US	0.19
1	US	0.2
1	US	0.21
0	FR	0.24
0	FR	0.23
0	FR	0.21
0	FR	0.22
1	FR	0.2
1	GB	0.1

Coefficients:
              Estimate Std. Error z value Pr(>|z|)
(Intercept)     -4.903      6.490  -0.755    0.450
countrycodeGB   20.877   3956.182   0.005    0.996
countrycodeUS    1.247      1.689   0.738    0.460
distance        15.916     28.809   0.552    0.581

Am I doing something wrong or if this is the expected result, would you be able to explain why is it so? This is just for my further understanding and reference. Thanks.

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