Cubic Spline
Smoother
The cubic spline scatterplot smoother
is a special smoothing technique for 2D
scatterplots, which generally produces a smooth generalization of
the relationship between the two variables in the scatterplot. The cubic spline smoother is often used
in generalized additive models,
to estimate the unspecific (non-parametric) function of the predictor
variables that best predicts the (transformed) dependent variable values.
Computational details regarding the cubic
spline smoother, and comparisons to other smoothing algorithms,
can be found in Hastie and Tibshirani, 1990, and Schimek, 2000.