---------- Forwarded message ---------- From: <r-help-owner@r-project.org> Date: Mon, Jan 14, 2013 at 12:31 AM Subject: Help with nonlinear regression To: ahmedatia80@gmail.com The message's content type was not explicitly allowed ---------- Forwarded message ---------- From: Ahmed Attia <ahmedatia80@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 <ahmedatia@zu.edu.eg>.attia@ag.tamu.edu Cell phone: 001-979-248-5215 [[alternative HTML version deleted]]
---------- Forwarded message ---------- From: Ahmed Attia <ahmedatia80 at gmail.com> Date: Mon, Jan 14, 2013 at 2:31 AM Subject: Help with nonlinear regression To: r-help at r-project.org Dears- 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.attia at ag.tamu.edu Cell phone: 001-979-248-5215