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Questions tagged [segmented-regression]

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1answer
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Segmented Regression of a Seasonal Time-series in R

I have a time-series of diurnal temperature range (DTR), 1961 - 2013 from a single weather station. Visually, the first part of the TS seems to have a downward trend, so I used the package ...
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0answers
21 views

Calculating standard error of coefficients in segmented regression

I know this is kinda stupid question to ask here but just to make sure that I am doing this correctly, here it is anyway: Consider the following equation resulted from segmented regression: $$\hat ...
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1answer
91 views

Segmented regression

I am working with data consisting of observations over time (abundance and harvest of different game species over several years). I am interested in finding if and when the direction is changed (i.e. ...
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0answers
46 views

Controlled interrupted time series (segmented regression) - determining the influence of a covariate on the observed treatment effect

I have conducted a controlled interrupted time series using Linden's formulation, where $Y_t = β_0 + β_1T + β_2X_t + β_3TX_t + β_4Z + β_5ZT + β_6ZX_t + β_7ZX_tT$ $β_0...β_3$ represent the control (...
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0answers
183 views

k-fold cross validation of segmented regression

I am solving a MILP problem in my current master thesis and I got stuck with some issue. Originally, I had it a set of data points that I was using to build an OLS regression model of second order. ...
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1answer
112 views

Controlled interrupted time series (segmented regression) - calculating group effects separately

I have conducted a controlled interrupted time series using Linden's formulation, where $Y_t = β_0 + β_1T + β_2X_t + β_3TX_t + β_4Z + β_5ZT + β_6ZX_t + β_7ZX_tT$ $β_0...β_3$ represent the control (...
2
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1answer
208 views

AIC/BIC for a segmented regression model?

Can AIC/BIC be calculated reliably for a segmented regression model? If so, can the results be compared against AIC/BIC calculations for non-segmented regression models on the same data?
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1answer
124 views

Applying offset correctly in an Interrupted Time Series Analysis using segmented regression in GLM in R [closed]

I would like to apply an offset to allow for the population within segmented regression using GLM on count data in R and need to ensure that the formula I am using is correct. Adding offset in 2 ...
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0answers
206 views

Interrupted Time Series Segmented Regression for Rates

I would like to test an intervention using interrupted time series (segmented regression). I have monthly rate (proportion) data with many of the rates in the <0.10 range. Should I use a standard ...
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0answers
661 views

Interpretation of Multivariate Adaptive Regression Splines (MARS) with Multiple Predictors

When it comes to multiple predictors, I've seen conflicting interpretations of MARS models and hoping for some clarification. Some fake results, let's say it's predicting household income via years ...
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76 views

How to find effect of treatment when there is no control group?

I am trying to study the effects of a program, where everyone gets treated. I have 50% of the population in t and the rest of the 50% in t+1 period. I understand this gives me a slight opportunity of ...
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0answers
144 views

Segmented linear regression with fixed number of break points

I would like to perform linear regression on a growth curve. Due to treatments I expect the growth to change not at all, once ore twice. Therefore I want to test wether my growth curve is best fitted ...
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0answers
99 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). ...
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2answers
194 views

Using segmented linear regression as evidence for the limit of human lifespan

Nature published this year the following paper: Evidence for a limit to human lifespan1, in which the authors argue their "results strongly suggest that the maximum lifespan of humans is fixed and ...
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0answers
446 views

Interrupted Time Series Analysis: Autocorrelation greater than 1?

I am running an interrupted time series analysis. (Basically, I run a "before" and "after" linear regression, and measure the change in Constant/y-intercept.) My objective: to measure the sudden drop ...
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0answers
55 views

Classifying according to relationship between variables

I do have a large dataset and would like to classify it according to the relationship between some variables. I do not want to use clusters, because clustering results groups that are similar. I do ...
2
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1answer
589 views

Segmented Regression With Control Group Implementation and Interpretation

I have been reading the following paper on segmented regression for interrupted time series - Wagner 2002 and wanted to learn a proper analysis of such data where there is a control group. The paper ...
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3answers
3k views

segmentation of univariate irregular time series

this is my first post. I have an irregular time series that exhibits large shifts in both mean and in the direction of the trend. It looks something like this (though this is far cleaner than ...
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2answers
813 views

How does one perform multiple non-linear regression?

I performed an experiment where I took the heights of plants and measured a number of environmental conditions (air temp, soil temp, lux, air humidity, soil pH, wind) for each of those plants. I want ...
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0answers
56 views

Multiple event for segmented regression?

Is there any statistical methods like segmented regression for many(>3) events? Recently, many policies in my field were introduced in a short period of time. I usually used segmented regression to ...
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1answer
4k views

Estimate number of breakpoints in regression

I've been playing around with the package strucchange (and to some extent segmented) in R. I'm trying to determine whether there ...
3
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1answer
210 views

Help constructing a simple regression model with a breakpoint

This is related to my questions here and here. I am still struggling with my model, so I am taking it back to basics. My assertion is simple, I believe that watershed runoff will have a different ...
2
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1answer
2k views

interrupted time series in R

I have Malaria incidence data from 2003 to 2013. There was intervention implemented in 2008. How can I do segmented regression analysis of interrupted time series in R to test whether the pre ...
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0answers
282 views

Model comparison: segmented GLM and GLM

I have two model comparison questions: First comparison: I have a GLM model and a segmented GLM model. both models have the same dependent and independent variables. The only difference is that we ...
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0answers
911 views

Using segmented package with multiple regression

I am trying to perform a relatively simple multiple regression with a single breakpoint using the segmented package in R. My question is how to handle the interaction between the predictor variables ...
6
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2answers
894 views

R - how to get standard error for a breakpoint/parameter in a piecewise regression

I'm new to asking questions here, so I hope this is a reasonable place for this. I am trying to fit a piece-wise regression. I expect my response (y) to increase from x0 to somewhere along x, then to ...
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2answers
1k views

Testing slopes in multivariate adaptive regression splines (MARS/earth)

I am using the earth package in R to estimate the number of breakpoints in a curve. There is only a single predictor. I was ...
2
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1answer
656 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),...
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0answers
1k views

Segmented regression in R: interpreting the other coefficients

I am running segmented regression using the R package 'segmented'. The original binomial logistic regression has two coefficients, approach_km (continuous), and sea (dichotomous) that explain the ...
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0answers
117 views

What is the correct specification for a segmented regression of interrupted time series data with a non-equivalent comparison group?

I know this is the general specification for a single group: $Y_i$ = $\beta_0$ + $\beta_1$*time + $\beta_2$*post + $\beta_3$*timepost where time is a continuous ...
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0answers
351 views

Find specific 'y' value from GLM-fitted segmented multivariate regression

I loaded the data to R and fitted it using GLM function. fit.glm = glm(y~ aX+bZ+cW) Then, I found the cuttinf-point using "segmented" tool of R. o<-segmented(fit.glm,seg.Z=~X,psi=10) Now I ...
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1answer
2k views

Statistical significance of breakpoints from `segmented` in R

I'm looking for breakpoints in species abundance as a function of spatial distance, using the segmented package for R. 'segmented' appears to return a breakpoint no ...
6
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2answers
3k views

Choosing the number of breakpoints for segmented regression (in R)

What methods/functions are available for choosing the number of breakpoints for segmented regression? Toy data/code for examples: ...
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0answers
190 views

Piecewise orthogonal (Deming) regression

I'm trying to calculate a single breakpoint on $x$ from several thousand $(x,y)$ points. Due to the density distribution as per the 2D histogram below, the least squares method is proving unsuitable. ...
4
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1answer
2k views

What are the pros and cons of segmented regression and regression with ARIMA errors for interrupted time-series analysis?

What are the pros and cons of segmented regression and regression with ARIMA errors for interrupted time-series analysis? In what situation would I choose one method over the other? Are there any ...