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Questions - non-linear-regression

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

Why does my nonlinear regression curve have straight line segments?

I try to draw a non-linear curve but I don't know why it has straight line segements. The original data is as below: ISIDOR <- structure(list(Pos_heliaphen = c("W30", "X41", &qu...
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Chouette

r

ggplot2

non-linear-regression

Votes: 0

Answers: 1

Latest Answer

You are only predicting at the x values already present in your data. The resulting predictions are joined up by straight lines. You need to feed the predict function the sequence of x values at which...
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Allan Cameron

Understanding the SSasymp function in R and its fitted values

I have run the following non linear model in r: model <- nls(y ~ SSasymp(x, Asym, R0, lrc), data = df_z) summary(model) Here is the output: Formula: y ~ SSasymp(y, Asym, R0, lrc) Parameters: ...
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pyring

r

statistics

curve-fitting

non-linear-regression

Votes: 0

Answers: 1

Latest Answer

You have the value of x outside the final bracket. It should be inside: xvals <- seq(0, 0.2, 0.001) yvals <- 1.114 + (2.01447 - 1.114) * exp(-exp(4.886) * xvals) plot(xvals, yvals, type = "...
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Allan Cameron

Non-linear fit regression

df <- data.frame(hour=c(5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23), total=c(15507,132129,156909,81306,44413,51448,55308,63542,57564,54031,70319,53345,35137,15509,20134,51...
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William.G.K

r

data-science

non-linear-regression

Votes: 0

Answers: 1

Latest Answer

"Best fit" is a question with a variety of answers depending on your goals, but: AIC(fit1,fit2,fit3,fit4,fit5) df AIC fit1 3 450.4892 fit2 4 451.8506 fit3 5 453.3828 fit4 6 454...
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Ben Bolker

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