It is not a human growth curve. The parameter estimates are about:
a = .5
b = 7
k = 1
It is not a sigmoidal curve as there is never a concave segment.

From: ml-node+3478241-1447170361-211414@n4.nabble.com [mailto:ml-node+3478241-1447170361-211414@n4.nabble.com]
Sent: Wednesday, April 27, 2011 09:15 AM
To: Thompson, Adele - Adele_Thompson@cargill.com
Subject: Re: How can I extract information from list which class is nls


On Apr 27, 2011, at 9:28 AM, Schatzi wrote:

> Here is more information on the equation. It is a growth function:
>
> Growth = a + b*(1-exp(-k*time))
>
> where a, b and k are parameters. I wanted to test the difference in
> total growth between treatments and the parameters a + b represent
> total growth. Thus, I figured that I could add the parameters and
> the SE to test the treatment differences. I also need the rate
> constant k and the initial values a and their treatment differences.
> I found the equation I posted on this website:
> http://sci.tech-archive.net/Archive/sci.math/2004-07/4780.html
> This book was referenced: Kendall & Stuart's Advanced Theory of
> Statistics

You should look at the vignettes and examples in the `fda` package.
fda == Functional Data Analysis and the authors have a book that adds
further background.

http://ego.psych.mcgill.ca/misc/fda/ex-growth-a2.html

You might also try:
RSiteSearch("growth curve")

--
David.

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