# Questions tagged [nls]

nls is an R routine to fit nonlinear regression models of the form $y = f(x B) + e$

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### Normalization of log-returns or normalization of cumulative log-returns

This questions seeks for discussion to find theoretical support for normalizing cumulative log-returns vs normalizing log-returns By "normalizing" (also known as standarizing) I mean it in ...
23 views

### Can I adjust lambda by 1 or 2 S.E. in exponential decay to potential improvements in retention

(Similar example data to a post I made posted yesterday but a completely different question) I have an exponential decay with off-set function that looks like this: ...
30 views

### Calculate non linear regression (nls()) prediction interval without a library

I wouldlike to know how to calculate a prediction interval manually, without using a library. Ultimate goal is to write some formula in a spreadsheet based on the model params that would let me ...
1 vote
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### Singular gradient errors in nls in R studio [closed]

I make fisheries work, and I need to estimate some parameters from the von Bertalanffy equation: Lt=Linf*(1-exp-K(t-t0)) here Linf, K, and t0 are the parameters that I want to estimate by FSA package ...
1 vote
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### How to weigh residuals based on x-interval in the nls() function in R?

A plot of my data and fit: ...
30 views

### NLS-estimated Discrete Bass Model (Satoh, 2001)

The above is the Satoh (2001) discrete derivative of the cumulative Bass model. I am using it to estimate a cumulative diffusion pattern from 19 years of data. (Renewable energy source diffusion in ...
1 vote
74 views

### fitting growth curves with nls singular gradient error [duplicate]

I'm having trouble fitting my model to a bacteria growth curve. I made a sample of my data below. Code: ...
56 views

### Significance of the p-values of the parameters in a non-linear model (using R)

I applied a logistic regression using the nlmrt package to describe the relationship between biomass and the distance and site variables. I got this result, but I ...
26 views

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### Sine curve fit using lm, nls and nls2 in R [closed]

I acquired data (motor adaptation =y in function of delays =t ) which I expect to look like a sine wave. I am trying (1) to fit a sine curve in my data and (2)to estimate the best model/parameters. I ...
1k views

### Comparing time series data between three treatment groups (in R)

I have time series data where the response is decreasing over time. The rate of the decrease is supposed to depend on the treatment (the concentration of a drug). By looking at the data I am not sure ...
1 vote
44 views

### r - Understand goodness of a fitted curve [duplicate]

I had to find the equation of curve that represent my data. After trying different function, I got a models that seems fitting my data, at least by plotting them. But this is it. I have no idea how to ...
2k views

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### Constraining parameters in NLS in R to be less than a value, or greater than a different value

The nls function in R comes with upper and lower arguments to specify the upper or lower ...
65 views

### Nonlinear fit in R only works with tightly restricting parameter bounds [duplicate]

I have a reproducible example here with an attempt to use nls to fit a nonlinear function: y = ax/(b+x) + c Even when I set the starting values to be a good, ...
3k views

### Singular gradient erros, NLS in R

I'm trying to fit nls(Mound~ a*kg.bag.collar^b + c, start = list(a = 83, b = -.5, c=100), data=test) using the dataset here. I've fit it without trouble without the ...
1 vote
1k views

### NLS model comparisons by ANOVA

I am comparing NLS models from two groups, males and females. I compared the models by ANOVAs, but I am hesitating which is the correct model comparison to use: a) Subgroup Males vs Subgroup Females b)...
279 views

### Trouble fitting my data with non-linear Regression model

I have a dataset that contains tree height and diameter measurements among the tree stem. I tried to fit my data with GNLS in R, but I'm getting this "step halving factor reduced below minimum in NLS ...
1 vote