Hello,


Is there a way to add up coefficients from a glm model for an ANCOVA to get
the coefficients for each term?

For example, in the following:
dat <- data.frame(response = rnorm(9), size = rnorm(9),  covariate =
c(1,1,1,1,0,0,0,0,0))
model <- glm(response ~ size * covariate, data = dat)
> coef(model)
   (Intercept)           size                covariate       size:covariate
    -0.2995964     -0.1969266      0.7158756      1.2829886

we are interested in the coefficients for the intercepts for size at both
levels of the covariate  (0 and 1), and the slopes for each line. This
requires adding up coefficients from the above output.

Are there built in base functions or in other packages that do these
additions?


Thanks!
__
Scott Chamberlain

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