R help - Apr 2009 - approximation function

Hi,
Having a set of values (non-time series data), what are the approximation
functions that could determine the trend of the values?

Cheers,

Carol


      
	[[alternative HTML version deleted]]

Hi,

This is a rather broad question.

The function lowess() might be a good place to start, I guess (although 
I'm not sure whether this fits in your definition of "approximation 
functions"...).

Best of luck,

Luc



carol white wrote:
> Hi,
> Having a set of values (non-time series data), what are the approximation
functions that could determine the trend of the values?
>
> Cheers,
>
> Carol
>
>
>       
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Hi,

At the sampling points, do you know the function value "exactly" or
you only observe it with "noise"?

If it is the former, you can use an interpolation scheme, such as, for example,
interpSpline() in "splines" package.

If it is the latter, you can use a smoother, such as, for example,
smooth.spline() or loess().

Ravi.
____________________________________________________________________

Ravi Varadhan, Ph.D.
Assistant Professor,
Division of Geriatric Medicine and Gerontology
School of Medicine
Johns Hopkins University

Ph. (410) 502-2619
email: rvaradhan at jhmi.edu


----- Original Message -----
From: carol white <wht_crl at yahoo.com>
Date: Monday, April 6, 2009 4:16 pm
Subject: [R] approximation function
To: r-help at stat.math.ethz.ch

> Hi,
>  Having a set of values (non-time series data), what are the 
> approximation functions that could determine the trend of the values?
>  
>  Cheers,
>  
>  Carol
>  
>  
>        
>  	[[alternative HTML version deleted]]
>  
>  ______________________________________________
>  R-help at r-project.org mailing list
>  
>  PLEASE do read the posting guide 
>  and provide commented, minimal, self-contained, reproducible code.