fitted is a generic function which extracts fitted values from
objects returned by modeling functions. fitted.values is an
alias for it. All object classes which are returned by model fitting functions
should provide a fitted method. (Note that the generic is
fitted and not fitted.values.) Methods can make use of napredict methods to compensate
for the omission of missing values. The default and nls
methods do.fitted(object, …)
fitted.values(object, …)object.coefficients, glm, lm,
residuals.