[S] loess vs lowess

Laffont, Jean-Louis (Laffont@phibred.com)
Fri, 26 Jun 1998 03:44:44 -0500


Dear S+ users,

I have been using the lowess function to add a smooth curve to my
scatter plots.
Now, I want to use the loess function but I am having trouble because I
am getting different results with the two functions. Here is an example:

> attach(ethanol)
> ethanol.loess<-loess(NOx~E,span=2/3)
>
plot(ethanol.loess,xlim=range(E),ylim=range(NOx,fitted(ethanol.loess)))
> points(E,NOx)
> lines(lowess(E,NOx,f=2/3),col=2)

The two curves are very different (visually, I prefer the one produced
with loess).
Am I leaving something out in setting up the parameters?

Thanks for your help.

Jean-Louis
(I am using S+ 4.5 Professional, release 1)

---------------------
Jean-Louis Laffont
Pioneer Semences
Aussonne - France
email: laffont@phibred.com

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