sigmaHat: Return the scale estimate for a regression model
Description
This function provides a consistent method to return the estimated scale
from a linear, generalized linear, nonlinear, or other model.
Usage
sigmaHat(object)
Arguments
object
A regression object of type lm, glm or nls
Value
A nonnegative number
Details
For an lm or nls object, the returned quantity is the square root of the
estimate of $\sigma$. For a glm object, the returned quantity is
the square root of the estimated dispersion parameter.