Questions tagged [dirichlet-regression]

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3answers
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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, ...
3
votes
1answer
1k views

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 ...
2
votes
0answers
15 views

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?
1
vote
1answer
64 views

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 ...
1
vote
2answers
403 views

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 ...
1
vote
1answer
51 views

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 ...
1
vote
0answers
15 views

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 $\...
1
vote
0answers
91 views

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 ...
0
votes
0answers
13 views

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). ...
0
votes
0answers
23 views

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 ...
0
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0answers
130 views

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 ...