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Questions - nls

why am I getting so strange t statistics and p values in the nls() output?

I'm running a nonlinear multiple regression with the nls() function with one dependent variable (Gross Primary Production (GPP)) and three independent variables (solar irradiance (RAD), Green Fraction...
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Fra AdV

r

regression

non-linear-regression

nls

Votes: 0

Answers: 1

Latest Answer

This is not a software problem. It is a fundamental problem with the model as it is not identifiable. If (F, a0, A1, A2, A3) is a solution then replacing it with (F/s, a0/s, sA1, sA2, s*A3) gives th...
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G. Grothendieck

How to use nls with caret to do cross-validation

I have fit several models using nls to the same data and am trying to figure out how to use caret to do K-fold cross-validation (eg., here). This SO question asked a general question about using nls i...
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D Kincaid

r

cross-validation

caret

nls

Votes: 0

Answers: 1

Latest Answer

You could do this with the vfold_cv() function in the rsample package, which is in the tidymodels ecosystem. df <- structure(list(c = c(123.86, 208.75, 141.5, 230.73, 143.4, 209.31, ...
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DaveArmstrong

ODE-based nonlinear least square in R

I have to set a nonlinear least square regressor on a function that comes from the integration of an ode. Something like #rm(list=ls()) library(deSolve) set.seed(1) # for reproducibility t = seq(0,2*...
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Fabio

r

nls

desolve

Votes: 0

Answers: 1

Latest Answer

You should apply the following corrections f = function(t, p) { # de integrated (times = c(0, t) to ensure first time = 0) ode(y = c(x = 0), func = dxdt, times = c(0, t), parms = p )[-1, 2] } sol ...
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Meysam

Extracting coefficients of non-linear equation across categorical variable

This question appears to be off-topic because it focuses on programming, debugging, or performing routine operations, or it asks about obtaining datasets. You could try the support links we maintain o...
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Daniel Fishburn

r

apply

curve-fitting

nls

nonlinear-equation

Votes: 0

Answers: 1

Latest Answer

For coefficients, use either coef to return a vector or summary.nls(...)$coefficients to return a matrix which also includes t-stats and p-values on results of nls(). To run model by groupings, consi...
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Parfait

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