# inconsistency in nls output....

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## inconsistency in nls output....

 dear members,                              I have the following nls output:  Formula: YLf13 ~ (d + e * ((XL)^(1/3)) + f * log(LM3 + 18.81)) Parameters:     Estimate Std. Error t value Pr(>|t|) d  5.892e-09  8.644e-10   6.817 2.06e-11 *** e -6.585e-09  5.518e-10 -11.934  < 2e-16 *** f  1.850e-10  2.295e-10   0.806     0.42 --- Signif. codes:  0 �***� 0.001 �**� 0.01 �*� 0.05 �.� 0.1 � � 1 Residual standard error: 9.57e-10 on 677 degrees of freedom Number of iterations to convergence: 2 Achieved convergence tolerance: 3.973e-08 ------ Residual sum of squares: 6.2e-16 ------ t-based confidence interval:            2.5%         97.5% d  4.195378e-09  7.589714e-09 e -7.668142e-09 -5.501342e-09 f -2.655647e-10  6.354852e-10 ------ Correlation matrix:            d             e             f d  1.0000000 -6.202339e-01 -7.832539e-01 e -0.6202339  1.000000e+00 -2.127301e-05 f -0.7832539 -2.127301e-05  1.000000e+00 if I let XL = 1.1070513 and LM3 = 0.3919 , and consider the coeffs as given above, the right hand side of the above equation is negative. But YLf13 is always positive! How is this possible? Am I interpreting the result of the nls output properly?  Should I interpret the coeffs differently? I have done hours of thinking over the above problem but couldn't find any results... I cannot provide the full values of YLf13, XL and LM3 due to IPR issues....please cooperate......however, if the only way to solve the problem is to give these values, I would indeed give them..... Also forgive me if there is a minor mistake in my calculations... or a typo.... very many thanks for your time and effort.... yours sincerely, AKSHAY M KULKARNI         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Fw: inconsistency in nls output....

 dear members,                             with reference to the attached message: I think I have found out the problem: YLf13 has the structure: YLf13 <- a*exp(-1000*LM1); LM1 is another vector. most of the YLf13 vector is getting populated with zeros, I think, because of the very low value of exp(-1000*LM1). Is there any method in R wherein I can work with these very low values? Or is the problem not related to the structure of YLf13? very many thanks for your time and effort... yours sincerely, AKSHAY M KULKARNI ________________________________________ From: R-help <[hidden email]> on behalf of akshay kulkarni <[hidden email]> Sent: Wednesday, March 6, 2019 6:02 PM To: R help Mailing  list Subject: [R] inconsistency in nls output.... dear members,                              I have the following nls output:  Formula: YLf13 ~ (d + e * ((XL)^(1/3)) + f * log(LM3 + 18.81)) Parameters:     Estimate Std. Error t value Pr(>|t|) d  5.892e-09  8.644e-10   6.817 2.06e-11 *** e -6.585e-09  5.518e-10 -11.934  < 2e-16 *** f  1.850e-10  2.295e-10   0.806     0.42 --- Signif. codes:  0 �***� 0.001 �**� 0.01 �*� 0.05 �.� 0.1 � � 1 Residual standard error: 9.57e-10 on 677 degrees of freedom Number of iterations to convergence: 2 Achieved convergence tolerance: 3.973e-08 ------ Residual sum of squares: 6.2e-16 ------ t-based confidence interval:            2.5%         97.5% d  4.195378e-09  7.589714e-09 e -7.668142e-09 -5.501342e-09 f -2.655647e-10  6.354852e-10 ------ Correlation matrix:            d             e             f d  1.0000000 -6.202339e-01 -7.832539e-01 e -0.6202339  1.000000e+00 -2.127301e-05 f -0.7832539 -2.127301e-05  1.000000e+00 if I let XL = 1.1070513 and LM3 = 0.3919 , and consider the coeffs as given above, the right hand side of the above equation is negative. But YLf13 is always positive! How is this possible? Am I interpreting the result of the nls output properly?  Should I interpret the coeffs differently? I have done hours of thinking over the above problem but couldn't find any results... I cannot provide the full values of YLf13, XL and LM3 due to IPR issues....please cooperate......however, if the only way to solve the problem is to give these values, I would indeed give them..... Also forgive me if there is a minor mistake in my calculations... or a typo.... very many thanks for your time and effort.... yours sincerely, AKSHAY M KULKARNI         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code. ATT00001.txt (424 bytes) Download Attachment