The calling sequence for cp
matches those for the
locfit
or locfit.raw
functions.
The fit is not returned; instead, the returned object contains
Cp criterion for the fit.
Cp is usually computed using a variance estimate from the largest
model under consideration, rather than
\(\sigma^2=1\). This will be done
automatically when the cpplot
function is used.
The Cp score is exact (up to numerical roundoff) if the
ev="data"
argument is provided. Otherwise, the residual
sum-of-squares and degrees of freedom are computed using locfit's
standard interpolation based approximations.
cp(x, ..., sig2=1)
model formula or numeric vector of the independent variable.
other arguments to locfit
and/or
locfit.raw
.
residual variance estimate.
locfit
,
locfit.raw
,
cpplot