I am trying to interpret the output of GLM and I am not sure how it is
treating the factor GENDER with levels G-M and G-F.

Below is the output of summary(GPA.lm)


Call:
glm(formula = zGPA ~ Units.Bfr.7A * GENDER, data = Master1)

Deviance Residuals:
    Min       1Q   Median       3Q      Max
-1.1432  -0.3285  -0.1061   0.2283   1.8286

Coefficients:
                         Estimate Std. Error t value Pr(>|t|)
(Intercept)            -2.513e-01  2.238e-02 -11.230  < 2e-16 ***
Units.Bfr.7A            2.297e-05  2.851e-04   0.081    0.936
GENDERG-M               3.183e-01  4.536e-02   7.018 2.56e-12 ***
Units.Bfr.7A:GENDERG-M -3.073e-03  5.975e-04  -5.142 2.82e-07 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

(Dispersion parameter for gaussian family taken to be 0.2432662)

    Null deviance: 1204.2  on 4875  degrees of freedom
Residual deviance: 1185.2  on 4872  degrees of freedom
  (106 observations deleted due to missingness)
AIC: 6950.8

Number of Fisher Scoring iterations: 2



second I would like to draw two lines w/ confidince intervals on the
scatter plot.  One for G-M and the other for G-F

I think I am doing this with
stat_smooth(aes(group=GENDER), method="glm", fullrange=TRUE)
 but again am not sure quite what is being outputted.

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