# Questions tagged [piecewise-linear]

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### Formula for cyclic continuous piecewise Regression

I am interested in running a piecewise linear regression in R. I would like to specify the model matrix for the piecewise regression myself so I am not interested in using a pre-coded solution from a ...
1answer
53 views

### Is there a formal test for model comparison between polynomial regression and piecewise/segmented regression? (i.e., are these models nested?)

I am interested in comparing three models a linear regression model: mod_linear <- lm (dv ~ iv) a polynomial regression model: mod_polynomial <- lm (dv ~ iv + I(iv^2)) a one-breakpoint ...
3answers
193 views

### Is there a “canonical” probabilistic version of the step function?

Step and switch-like functions can be thought of as deterministic switches at some threshold, so smooth sigmoidal-like functions describe that switch with uncertainty around that value. The machine ...
0answers
100 views

### Generalized Linear Model in a Piecewise SEM?

I have applied a piecewise structural equation model to my data using generalised linear models. I have used the glm() R function along with psem in the "piecewiseSEM" R package. It has ...
1answer
97 views

### How to fit a piecewise assembly of nonlinear functions?

I am trying to model vegetation spectral signatures (grey lines) using a two-part piecewise function (black dotted lines). In it, I am trying to use only a few points (red dots) to fit a linear (first ...
2answers
113 views

### How do you fix one slope coefficient in an interaction term?

hoping someone can help me with what (on the face of it) appears to be a relatively simple problem but which I can't current code out. Basically, I would like to fit a GLM in R with a simple two-way ...
0answers
29 views

### How do I calculate the standard error and p value for a piecewise linear mixed model with lmer?

I have fit a piecewise spline linear mixed model with multiple knots: ...
1answer
255 views

### In hierarchical regression, the first step is not significant but later steps are

I ran a hierarchical regression comparing different models, in order of complexity. The first step was not significant (the simplest model vs a more complex model). However the next two steps were ...
1answer
45 views

### Select model in piecewise regression

How could we compare models fitted with piecewise regression that have different breakpoints? I used the code written here. In the example below, the "best" model, i.e. minimizing the residuals is ...
2answers
59 views

### Simple algorithm to detect change point in time series

Apologies if this question has already been asked, but a lot of similar questions are regarding R or complex algorithms that I don't want. I have numerous 2-dimensional time series, eacch plotting ...
1answer
331 views

### How to do a discontinuos segmented logistic regression in R?

I'm trying to do a discontinuous segmented logistic regression, something like this: https://imgur.com/ON4k1hy . The 6 breaking points are predetermined from domain knowledge. Unfortunately my ...
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### Censoring linearly splined predictor in regression

I'm developing a logistic regression where one of the independent variables has a non-linear relationship to the probability of the event occurring. I have created linear splines based on this ...
1answer
501 views

### Position of knots in piecewise linear regression as 'random effects'

TL;DR: Is there some way I can do 'random knots' (where the position of the knot varies according to some group, not the number)? Full question: After obtaining experimental data, I find that one of ...
2answers
481 views

### Piecewise regression vs multiple models

Say you have a piecewise regression model with one breakpoint. Is there any difference between that and just creating a separate simple regression model for each segment of the IV?
0answers
389 views

### Understanding the Math of Segmented and Splines2 packages.

I was trying to teach myself the math behind what produces the slope and intercept of a segmented variable in the segmented package using the plant data set. My ...
0answers
242 views

### Looking for references - ReLU neural networks vs Fitting continuous piecewise linear function

ReLU activated neural networks with a linear output are continuous piecewise linear functions (CPLF). There are technuques to fit CPLF functions, so comparison of those methods seems very natural, ...
1answer
193 views

### How to adjust the parameters of a Piecewise regression model in Matlab?

I have an existent piecewise regression model correlating the parameters X and Y as follows: If X<0.1, then Y=0.744. If X>=0.1 & X<=0.8, then Y=0.842-0.977*X. If X>0.8, then Y=0.06. The ...
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153 views

### Finding an inflection point between two conditions

The figure below illustrates a sample data from a numerosity estimation experiment with an uncalibrated (i.e., spontaneous) estimation condition (blue) and a calibrated estimation condition (orange). ...
1answer
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### piecewise regression into a for loop [closed]

I´m trying get a piecewise regression. ...
0answers
427 views

### Model with piecewise-linear functions

I have a model which is of the following deterministic form: Y = A + B + C A, B and C are piecewise-linear functions of a, b and c, which are macroeconomic variables. I have the values (nodes, ...
1answer
341 views

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### Weighted piecewise regression to model proportion?

I was trying to model the relationship between utilization of service (from 0 to 1) and travel distance. First I binned travel distance by each 20 km and then calculate utilization for each bin (count ...
0answers
1k views

### Is segmented (piecewise) regression possible with a dichotomous dependent variable?

I have created a model of American cities with a dichotomous Y variable using logistic regression. I have theoretical reasons to believe that the model will differ significantly between larger and ...
1answer
2k views

### Piecewise regression

I have a time series where I want to fit a piecewise regression equation. Now the problem occurs when I try to fit equations of different degree in different segments of the series. Please provide me ...
1answer
207 views

### Are the slopes of two segmented lines important in recognition of a breakpoint?

I have found one breakpoint in my linear regression but the slope of two lines have the same decreasing slope, I was wondering if the change of the slope is necessary in recognition of breakpoints.
1answer
906 views

### Adding additional terms to a piecewise regression

I am exploring the probability of flight in a seabird (1=flight, 0=no flight) using binomial logistic regression. My predictors are distance to a disturbance (continuous), hour of the day (continuous),...
0answers
716 views

### Estimating break point in a broken stick / piecewise linear model for one variable while including other as model terms

I am interested in estimating a break point in response to one explanatory variable, while also including other variables as terms in the linear model. One reason to include additional terms is to ...