# Questions tagged [nonlinear-regression]

Use this tag only for regression models in which the response is a nonlinear function of the parameters. Do not use this tag for nonlinear data transformation.

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### Exponential curve fitting with a constant

Assuming I have the following model: $$y(t) = \alpha {e}^{- \beta t} + \gamma + n(t)$$ Where $n(t)$ is additive white Gaussian noise (AWGN) and $\alpha, \beta, \gamma$ are the unknown ...
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### Log-normal distribution versus chi-square distribution for comparing RMSE of nonlinear fits

I have parameter estimates fitting a particular nonlinear model for thousands of experimental cycles. My goal is to find a nice way to tag those cycles which didn't fit the model very well. Currently ...
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### Uncertainties on parameters from maximum likelihood fitting

I am trying to fit a model to binomially distributed data, which I have done via the maximum likelihood method. Normally I'm working with normally distributed data (or data which I can convince myself ...
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### Normalizing error variance scale

Imagine we have two sets of data m1 and m2. m1 components have the dimension of [m^2/s] and m2 components are measured in [cm^2/s]. e.g. ...
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### Putting limits on estimated coefficient values

I recently came across an example of using eviews to put non-linear/convex limits on estimated coeficients on OLS. I could track down a link to a forum describing how this is done (here)... But I ...
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### How to select best model out of linear, quadratic, and a model involving an exponential? Are the models nested?

I'm examining the growth rate of species en function of ion carbonate. For each specie, I have different measured of ion carbonate, it can be in different temperature or pH. For each measure, I'm ...
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### How to find the “optimal” cutoff-points in a non-linear relationship?

I have the following challenge: The dataset has one dependent and one independent variable which are connected in a non-linear fashion. I am trying to give a more qualitative picture here because I am ...
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### Geometric circle fitting with known radius

I have data points from a half circle and I already know the radius. I want to find the circle which best fits the points using a fixed radius. How can I do this? If I solve the problem using a ...
316 views

### Nonlinear models which are hard to estimate

Genetic algorithms are avoided in econometry literature as often as possible, but still sometimes they are inevitable. The question is: Which well known models are the most difficult to estimate using ...