R help - Aug 2005 - Question about curve fitting...

Meta:
This question is somewhat long and has two parts, I would be very happy
for someone just to nudge me in the right direction with the manual /
tutorial, as I am somewhat lost...


1) How do I fit a curve of the form "y = k1 * x^k2" ?

I want to estimate values of k1 and k2 given the x/y data I have, and I
can't work out how to get R to calculate and return their estimates.


2) Given the value of k1 and k2 for population A, how can I test if
population B has significantly different values of k1 and k2?

Sorry for the basic question. I think I just need to read up on a few
functions.


I have about 50 xy pairs in total if that makes a difference.

Dan.

I see that 
log(y)=log(k1)+k2*log(x)
use lm?

----- Original Message -----
From: Dan Bolser <dmb at mrc-dunn.cam.ac.uk>
Date: Wednesday, August 10, 2005 11:41 am
Subject: [R] Question about curve fitting...
> 
> Meta:
> This question is somewhat long and has two parts, I would be very 
> happyfor someone just to nudge me in the right direction with the 
> manual /
> tutorial, as I am somewhat lost...
> 
> 
> 1) How do I fit a curve of the form "y = k1 * x^k2" ?
> 
> I want to estimate values of k1 and k2 given the x/y data I have, 
> and I
> can't work out how to get R to calculate and return their estimates.
> 
> 
> 2) Given the value of k1 and k2 for population A, how can I test if
> population B has significantly different values of k1 and k2?
> 
> Sorry for the basic question. I think I just need to read up on a few
> functions.
> 
> 
> I have about 50 xy pairs in total if that makes a difference.
> 
> Dan.
> 
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