Use this tag for regression models (*q.v.*) that are nonlinear functions of the *parameters* (not the data!).
3
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98 views
Relaxing the parallel lines assumption in a proportional odds model
I tried to specify a partial proportional odds regression in STATA using the gologit2 command.
However, gologit2 runs ...
3
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0answers
88 views
Shifted intercepts in logistic regression
I have a question about the effects of shifting the intercept in a logistic fit on the mean of a particular transformation of the scores.
Here is the notation I will be using for the question. The ...
3
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0answers
286 views
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 ...
2
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0answers
66 views
Exponent for non-linear regression (in R)?
I have a non-linear reglationship and I want to find the best way to determine the value for the exponent $\gamma$ in the following regression:
$y = \beta x ^ \gamma$
I would preferably like to do ...
2
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0answers
74 views
Monte Carlo confidence interval for general inverse problem
I am trying to solve an inverse problem, and I'd like to be able to compare different ways of doing the inversion.
What I don't understand how to do, is generate confidence intervals to help in the ...
2
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0answers
49 views
Gauss-Newton method for MA parameter estimation
Please check my solution below for estimating Moving Average parameter using the Gauss-Newton (Linearization) method. I consider MA(1).
MA(1) model:
$$z_t=a_t-\theta_1a_{t-1}.$$
Solution:
The ...
2
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0answers
63 views
dose response and lethal dose 50 analysis
I am going to perform an experiment to test for the pathogenicity of several bacterial strains. For this I will infect several animals (e.g. 5 per dose per bacterial strain) with increasing doses of ...
2
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0answers
66 views
How does one build/find a mathematical model for a convex relationship?
I think my various questions on this site about spline and polynomial regression boil down to this:
I have many datasets to analyze where individuals grow over time and, depending on treatment group, ...
2
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0answers
88 views
AR1 Modelling using dlmModReg
I'm trying to model AR1 using dlmModReg(). The main purpose is to keep phi a variable so that if phi >1, I know that mean reversion is not occurring.
Below is my ...
2
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0answers
377 views
Intuitive explanation of Gauss-Newton regression
I read from a textbook that Gauss-Newton regression is also called 'artificial regression'. Please give me an example, how does it work? And what's the relation with Newton's method? Thank you.
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22 views
Zero to one proportion data, with quadratic term?
I have a data set with the following:
N = 60;
x = developmental stage (range 25 to 44);
y = proportion of 10 minute trial performing a behavior (range 0 to 0.81; 30 zeros)
A scatterplot produces a ...
1
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0answers
65 views
Finding starting values for nls for critical exponential function
I'm trying to fit a critical exponential function using nls. The function is of the form $y = a+ (b + cx)r^x$ and has a single maximum/minimum, a single inflection ...
1
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181 views
Comparing model fits or regression coefficients for nonlinear models fitted to different data sets
I have kinetic data measured under several treatments (one experiment per treatment) which can be fitted by several nonlinear two-parameter models, how can I compare whether there there are ...
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0answers
49 views
Breakpoints and non linear regression
I have done some research about breakpoints (I am not a statistician) and I found out about the breakpoint, strucchange and segmented packages in R allowing to find breakpoints assuming linear model.
...
1
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0answers
166 views
Whether to use linear regression or not
Effects of growth hormone (GH) replacement with recombinant human GH on bone and mineral metabolism were studied in 36 GH-deficient children. Several outcomes, including serum ionized calcium levels, ...
