# Questions tagged [dirichlet-regression]

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### 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). ...
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 ...
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?
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 ...
402 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 ...
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 ...
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 ...
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 \$\...
3k views

### 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, ...