LOWESS
The LOWESS aka LOESS procedure is carried out in two phases: (1)
initial fit, and (2) robustness iterations to reduce the influence of extreme
observations (outliers).
The following three exhibit illustrate how the LOWESS algorithm works.
Created 20 Jan 2003
![Exhibit: Initial fit for a point with x-value inside the range of x, with a = 0.5 (a is width of "window", i.e. proportion of observations used in calculating the fitted value corresponding to x) (Cleveland 1994, Figure 3.49 p. 177) [lowess01.gif]](lowess01.gif){kind=link}
![Exhibit: Initial fit for a point on the boundary of the range of x (Cleveland 1994, Figure 3.50 p. 178) [lowess02.gif]](lowess02.gif){kind=link}
![Exhibit: Robustness iterations to reduce influence of outliers (Cleveland 1994, Figure 3.51 p. 179) [lowess03.gif]](lowess03.gif){kind=link}