[R] Interpreting as.factor

[Gabor Grothendieck]

Try this:

model.matrix(y ~ x + as.factor(x1))

to see the model matrix that is being used.  Matrix multiplication of
that matrix by the coefficients is the prediction equation.

On 6/23/06, Justin Rapp <justin.rapp at gmail.com> wrote:
> When I run a linear regression and include a variable in the
> regression with as.factor  i.e.
>
> lm(y ~x +as.factor(x1)
>
> and i read the output as
> as.factor(x1)1....
> as.factor(x1)2...
> etc.
>
> how do i interpret the estimate for each level?  Is this simply to be
> regarded as a shift in the equation predicted by the intercept and
> independent variable x?
>
> jdr
>
>
> --
> Justin Rapp
> 409 S. 22nd St.
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