[R] Forcing the extrapolation of loess through the origin

[Bert Gunter]

Below. 


Bert Gunter
Genentech Nonclinical Biostatistics
650-467-7374

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of jimm-panse at gmx.de
Sent: Tuesday, April 14, 2009 10:08 AM
To: r-help at r-project.org
Subject: [R] Forcing the extrapolation of loess through the origin

Hi all,

I'm fitting a line to my dataset. Later I want to predict missing values
that exceed the [min,max] interval of my empirical data, therefore I choose
surface="direct" for extrapolation.

l1<-loess(y1~x1,span=0.1,data.frame(x=x1,y=y1),control=loess.control(surface
="direct"))

In my application it is highly important that the fitted line intercepts at
the point of origin. Is it possible to do this in R?

-- No. Indeed, this appears to me to contradict the nature of loess as a
locally adaptive fit.
Bert

Thanks in advance.

Cheers,
Torsten
--

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