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+3478241-1447170361-211...@n4.nabble.com [mailto:ml-node+3478241-1447170361-211...@n4.nabble.com] Sent: Wednesday, April 27, 2011 09:15 AM To: Thompson, Adele - adele_thomp...@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. To unsubscribe from How can I extract information from list which class is nls, click here<http://r.789695.n4.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=804151&code=YWRlbGVfdGhvbXBzb25AY2FyZ2lsbC5jb218ODA0MTUxfC03MzgxNjM2NTM=>. ----- In theory, practice and theory are the same. In practice, they are not - Albert Einstein -- View this message in context: http://r.789695.n4.nabble.com/How-can-I-extract-information-from-list-which-class-is-nls-tp804151p3478367.html Sent from the R help mailing list archive at Nabble.com. [[alternative HTML version deleted]] ______________________________________________ R-help@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.
