---------- Forwarded message ----------
From: <r-help-ow...@r-project.org>
Date: Mon, Jan 14, 2013 at 12:31 AM
Subject: Help with nonlinear regression
To: ahmedati...@gmail.com
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---------- Forwarded message ----------
From: Ahmed Attia <ahmedati...@gmail.com>
To: r-help@r-project.org
Cc:
Date: Mon, 14 Jan 2013 00:31:41 -0800
Subject: Help with nonlinear regression
Hi-
I have a question about nonlinear regression.
*Asymptotic Regression Model**
* * below is the equation of the model (Reference the R book page 662)*
y = a - b e^-cx when I compensate x with 50 for instance, I get a very high
value does not match the graph produced by the same model (Asymptotic
regression model).
below is the output analysis from R;
Formula: GN1 ~ SSasymp(nrate, a, b, c)
Parameters:
Estimate Std. Error t value Pr(>|t|)
a 12.8190 0.4407 29.09 8.92e-05 ***
b 5.7249 0.2803 20.42 0.000257 ***
c -4.6697 0.1703 -27.41 0.000107 ***
---
Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1
Residual standard error: 0.2874 on 3 degrees of freedom
Number of iterations to convergence: 0
Achieved convergence tolerance: 7.184e-06
>
based on these coefficients should y= 12.81 5.72 e4.66x ?
the predicted lines indicate that the model works fine, but I do not know
how to compensate x in the equation to get y
AA
--
Ahmed M. Attia
Research Assistant
Dept. Of Soil&Crop Sciences
Texas A&M University
ahmed <ahmeda...@zu.edu.eg>.at...@ag.tamu.edu
Cell phone: 001-979-248-5215
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