R help - Aug 2011 - what characteristics of model curve do parameters denote

Dear list,

I'm trying to fit a chapman-richards equation to my data, only I
cannot interpret the parameters a, b and d. I know that the parameter
b denotes the asymptote, but for the others I couldn't figure out. But
I do need to know this in order to set my starting values. Here's the
model:

modPoplar<- nls(Diameter ~ d*(1-exp(-b *Age))^a ,start=list(a=20,b=0.9,d=33))

I attached the graph, too.

Hoping for your answers!

Best, Anna
-- 


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - -

Telefon: 01577-7805329
E-Mail: gretschel.anna at googlemail.com

Dear list,

I'm trying to fit a chapman-richards equation to my data, only I
cannot interpret the parameters a, b and d. I know that the parameter
b denotes the asymptote, but for the others I couldn't figure out. But
I do need to know this in order to set my starting values. Here's the
model:

modPoplar<- nls(Diameter ~ d*(1-exp(-b *Age))^a ,start=list(a=20,b=0.9,d=33))

I attached the graph, too.

Hoping for your answers!

Best, Anna

-- 



Der Inhalt dieser E-Mail ist vertraulich. Sollte Ihnen die E-Mail
irrt?mlich zugesandt worden sein, bitte ich Sie, mich unverz?glich zu
benachrichtigen und die E-Mail zu l?schen.

This e-mail is confidential. If you have received it in error, please
notify me immediately and delete it from your system.

Please refer to the posting guide... This is not a mathematics tutoring list.
Your question does not appear to be about R, so no one has responded.
---------------------------------------------------------------------------
Jeff Newmiller The ..... ..... Go Live...
DCN:<jdnewmil@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
Live: OO#.. Dead: OO#.. Playing
Research Engineer (Solar/Batteries O.O#. #.O#. with
/Software/Embedded Controllers) .OO#. .OO#. rocks...1k
--------------------------------------------------------------------------- 
Sent from my phone. Please excuse my brevity.

Anna Gretschel <gretschel.anna@googlemail.com> wrote:

Dear list,

I'm trying to fit a chapman-richards equation to my data, only I
cannot interpret the parameters a, b and d. I know that the parameter
b denotes the asymptote, but for the others I couldn't figure out. But
I do need to know this in order to set my starting values. Here's the
model:

modPoplar<- nls(Diameter ~ d*(1-exp(-b *Age))^a ,start=list(a=20,b=0.9,d=33))

I attached the graph, too.

Hoping for your answers!

Best, Anna
-- 


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - -

Telefon: 01577-7805329
E-Mail: gretschel.anna@googlemail.com

_____________________________________________

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.


	[[alternative HTML version deleted]]