Questions tagged [dirichlet-regression]
12 questions
32
votes
3 answers
Why Beta/Dirichlet Regression are not considered Generalized Linear Models?
The premise is this quote from vignette of R package betareg1.
Further-more, the model shares some properties (such as linear
predictor, link function, dispersion parameter) with generalized
linear models (GLMs; McCullagh and Nelder 1989), but…
Firebug
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4
votes
1 answer
Interpretation of the Precision Model in Dirichlet regression
I use dirichlet regression to analyze the result of a membership matrix (compositional data). For each observation, I have membership probabilities to different groups and these probabilities sum to one. For sake of simplicity, let’s say that I have…
Matthias Studer
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2
votes
1 answer
How does one Interpret a Dirichlet regression output?
I have been exploring the Dirichlet regression in R to analyze my ecological dataset and in the summary output is have several coefficient estimates. How do I interpret this output?
Nicholas_K
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2
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0 answers
Restriction and dependence in the Dirichlet distributon
The Dirichlet distribution is sometimes said that it is "too restrictive and imposes strong conditions on the dependence between components". What is the reason?
Tky
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1
vote
1 answer
How to deal with negative proportions in Dirichlet Regression
I am trying to work on a Dirichlet regression problem where I look at three true proportions the first two are actually measured while the third is computed as the complement:
$$p_3=1-p_1-p_2$$
The issue that I have is that $p_1$ and $p_2$ are…
user6384
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1
vote
2 answers
Is it possible to fit a Dirichlet Regression to changing response variables?
A toy problem to illustrate my issue:
We put a 100 people in a room with 10 candy bars. Each bar is different and has a different brand, flavor, size, color, etc. We ask each person in the group to choose the candy bar that looks the most…
George
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1
vote
1 answer
Modeling probability mass over time for prediction
Consider a discrete random variable $X$ with three possible realizations $x_1,x_2,x_3$. This variable is observed over time, with the number of observations per point in time varying.
The top figure below shows the probability for the three…
deemel
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1
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Including features in a Dirichlet model with Markov dynamics
I have a fantasizing about a model here, so please keep in mind that this is not even half-baked:
I have categorical time series data $y_t\sim\text{Cat}(y\ |\ \lambda_t)$ with a hidden variable $\lambda_t\sim\text{Dir}(\lambda\ |\…
tenticon
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1
vote
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Dirichlet-Regression: Indicator for variable fit in model comparison
I have a number of Dirichlet regression models with differing forms (log, linear, polynomial etc) over a dirichlet distribution of 6 variables/Groups.
An examplary output for summary(fit) in r would…
Igel_in_aspic
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0
votes
0 answers
Model selection and interaction terms in multivariate regression analysis of compositional data (Dirichlet regression)
I am currently exploring Dirichlet regression models to model fatty acid compositional data. I am using 2 categorical predictors and 1 continuous predictor (treatment group, sex, and total lipids).
When it comes to model selection, according to…
ms13
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Compare dependent categories over time?
I have a dataset with 50 individuals. 25 are exposed to a substance on low concentration, 25 are exposed to a substance on high concentration over time.
I have 4 categories that represent different states of an individual. e.g. "searching", "doing…
MriRo
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0
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Is fair to compare Dirichlet to a Multivariate Beta regression?
I am conducting some analysis on my data I found a strange behavior and would greatly appreciate some guidance or suggestions.
I am trying to investigate the effect of a categorical variable (cl) to three percentages that sum 1 (M). Naturally, I…
andremrsantos
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