[R] R exponential regression

[Murray Cooper]

Chris,

I haven't seen anyone post a reply yet so thought I'd
throw in my thoughts. I'm no R expert!

When you talk about an exponential trend line are you
refering to:

1)  y=ax^b
or
2) y=ae^(bx)

If 1) then take base10 logs of y and x and then fit them
with simple linear regression. Then calculate the antilog
of the residulas and plot these as your trendline.

If 2) then take natural logs of y and x and follow the rest
of the procedure described in 1).

Hope this helps.

Murray M Cooper, Ph.D.
Richland Statistics
9800 N 24th St
Richland, MI, USA 49083
Mail: richstat at earthlink.net

----- Original Message ----- 
From: "chrisli1223" <chrisli at austwaterenv.com.au>
To: <r-help at r-project.org>
Sent: Thursday, January 07, 2010 10:33 PM
Subject: [R] R exponential regression


>
> Hi all,
>
> I have a dataset which consists of 2 columns. I'd like to plot them on a 
> x-y
> scatter plot and fit an exponential trendline. I'd like R to determine the
> equation for the trendline and display it on the graph.
>
> Since I am new to R (and statistics), any advice on how to achieve this 
> will
> be greatly appreciated.
>
> Many thanks,
> Chris
> -- 
> View this message in context: 
> http://n4.nabble.com/R-exponential-regression-tp1009449p1009449.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>