Re: [R] display of a loess fitted surface

From: Prof Brian Ripley <>
Date: Fri 19 Aug 2005 - 01:59:57 EST

On Thu, 18 Aug 2005, Marta Colombo wrote:

> I am Marta Colombo,student at Politecnico,Milan. I am studying local
> regression models and I am using loess function. My problem is that when
> I have a loess object I don't know how to display the fitted surface; in
> fact, while in S when you have a loess object you can see it writing
> plot(object), in R this dosen't work.

Why not use S if that does what you want?

There are examples using R in MASS, for example: see the ch04.R and ch15.R scripts.

> Also I'd like to know if there is something like the S function
> pointwise that computes upper and lower confidence intervals.

(Do you mean upper and lower confidence limits?)

Thats a more general question. Many of R's predict() methods can construct confidence (and tolerance) intervals. If not, it is easy to do this yourself, as pred_obj$fit-/+pred_obj$se*qnorm(alpha/2).

Brian D. Ripley,        
Professor of Applied Statistics,
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Received on Fri Aug 19 02:04:39 2005

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