fitting curve to data

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I have the following data:
y
[1] 0.000 0.004 0.008 0.016 0.024 0.032 0.044 0.064 0.072 0.088 0.108 0.140
[13] 0.156 0.180 0.208 0.236 0.264 0.296 0.320 0.360 0.408 0.444 0.472 0.524
[25] 0.576
x
[1]  100  200  300  400  500  600  700  800  900 1000 1100 1200 1300 1400 1500
[16] 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500

I'd like to plot the points and calculate a curved line of best fit. I know I need to use nls(), but
I'm unsure how to begin....any pointers?

Cheers,
Nathan

- --
- --------------------------------------------------------
Dr. Nathan S. Watson-Haigh
OCE Post Doctoral Fellow
CSIRO Livestock Industries
Queensland Bioscience Precinct
St Lucia, QLD 4067
Australia

Tel: +61 (0)7 3214 2922
Fax: +61 (0)7 3214 2900
Web: http://www.csiro.au/people/Nathan.Watson-Haigh.html
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First, try plot(x,y)

If you want to use nls, you have to specify a nonlinear function to fit
to your data. See ?nls.

If you are really stuck on how to fit regression models, you should
consult a statistician (CSIRO has a lot of expertise).

Simon.
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I have the following data:

y
 [1] 0.000 0.004 0.008 0.016 0.024 0.032 0.044 0.064 0.072 0.088 0.108 0.140
[13] 0.156 0.180 0.208 0.236 0.264 0.296 0.320 0.360 0.408 0.444 0.472 0.524
[25] 0.576
x
 [1]  100  200  300  400  500  600  700  800  900 1000 1100 1200 1300 1400 1500
[16] 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500

I'd like to plot the points and calculate a curved line of best fit. I know I need to use nls(), but
I'm unsure how to begin....any pointers?

Cheers,
Nathan

- --
- --------------------------------------------------------
Dr. Nathan S. Watson-Haigh
OCE Post Doctoral Fellow
CSIRO Livestock Industries
Queensland Bioscience Precinct
St Lucia, QLD 4067
Australia

Tel: +61 (0)7 3214 2922
Fax: +61 (0)7 3214 2900
Web: http://www.csiro.au/people/Nathan.Watson-Haigh.html
- --------------------------------------------------------

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______________________________________________
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.
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
Faculty of Biological and Chemical Sciences 
The University of Queensland 
St. Lucia Queensland 4072 
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au

Policies:
1.  I will NOT analyse your data for you.
2.  Your deadline is your problem.

The combination of some data and an aching desire for 
an answer does not ensure that a reasonable answer can 
be extracted from a given body of data. - John Tukey.
As x goes from 200 to 400, y goes from ,004 to .016 so y is
quadrupling while x doubles -- quadratic growth.    Fitting
to a quadratic and plotting shows this to be the case.  Note
that for y to be quadratic in x it must be linear in the coefficients
of x so we can just use lm and don't need nls:

plot(y ~ x)
y.lm <- lm(y ~ poly(x, 2))
lines(x, fitted(y.lm))
y.lm

On Sun, Jan 11, 2009 at 9:19 PM, Nathan S. Watson-Haigh
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I have the following data:

y
 [1] 0.000 0.004 0.008 0.016 0.024 0.032 0.044 0.064 0.072 0.088 0.108 0.140
[13] 0.156 0.180 0.208 0.236 0.264 0.296 0.320 0.360 0.408 0.444 0.472 0.524
[25] 0.576
x
 [1]  100  200  300  400  500  600  700  800  900 1000 1100 1200 1300 1400 1500
[16] 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500

I'd like to plot the points and calculate a curved line of best fit. I know I need to use nls(), but
I'm unsure how to begin....any pointers?

Cheers,
Nathan

- --
- --------------------------------------------------------
Dr. Nathan S. Watson-Haigh
OCE Post Doctoral Fellow
CSIRO Livestock Industries
Queensland Bioscience Precinct
St Lucia, QLD 4067
Australia

Tel: +61 (0)7 3214 2922
Fax: +61 (0)7 3214 2900
Web: http://www.csiro.au/people/Nathan.Watson-Haigh.html
- --------------------------------------------------------

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r+AAnRD3kbkImG3rVaBN6d4BP2cUmqYZ
=yVLj
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______________________________________________
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.