# Tagged Questions

82 views

### Compare two regression models with same degrees of freedom

I have fit a non-linear model with 3 parameters to a data set. I have a preconceived notion that one of the parameters will be one of 2 values. So I would like to compare 2 fits of the same model ...
199 views

### statistical test to see if relationship is linear or non-linear

I have an example data set as follows: ...
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### Comparing sets of parameters extracted from different exponential fits to each other for significance

I take two simultaneous measurements from two different regions of a biological system, where both signals can be modelled by simple exponential rise and decay:  ...
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### Model selection with nonlinear fitting? Statistical tests seem ambiguous

I'm working on fitting an exponential model $\mathrm{Flux} = A+Bt+F\left(\exp(t_0-t/T_r) + \exp(t-t_0/T_f)\right)^{-1}+...$ to astronomical data (a light curve). $A$, $B$, $F$, $t_0$, $T_r$, and ...
166 views

### Residual, linear least squares and quality engineering

I wanted to ask this question on stackoverflow but I think it is more suitable here. If I am wrong, please tell me. My question concerns the use in statistics to analyse physical/engineering data. As ...
846 views

### How to read the the goodness of fit on nls of R?

I am trying to interpreting the output of nls(). I have read this post but I still don't understand how to choose the best fit. From my fits I have two outputs: ...
354 views

### Pseudo-$R^2$: what are the null models for linear and non-linear regressions?

I have data from an experiment. The independent variable is time, the dependent variable is mass loss of organic matter. Now I want to compare whether a linear or a non-linear model fits better. From ...
I have a nonlinear model $y=\Phi(f(x,a)) + \varepsilon$, where $\Phi$ is the cdf of the standard normal distribution and f is nonlinear (see below). I want to test the goodness of fit of this model ...