Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Distributions Gallery: Add LogitNormal #560

Merged
merged 2 commits into from
Oct 8, 2024

Conversation

aleicazatti
Copy link
Collaborator

No description provided.


The logit-normal distribution, also known as the logistic normal distribution, is a continuous probability distribution of a random variable whose [logit](https://en.wikipedia.org/wiki/Logit) (or log-odds) is normally distributed. Thus, if a random variable $X$ follows a logit-normal distribution, then $ Y = \text{logit}(X) = \log\left(\frac{X}{1-X}\right)$ is normally distributed. It is defined for values of $x$ between 0 and 1. It is characterized by two parameters: $\mu$ and $\sigma$, which are the mean and standard deviation of the logit-transformed variable, respectively, not the original variable.

The logit-normal distribution is useful in modeling proportions or ratios. In Bayesian modeling the logit-normal distribution is sometimes used as an alternative to Dirichlet priors for BART (Bayesian Additive Regression Trees), as it allows for a more flexible correlation structure between the predictors.
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This distribution being an alternative to the Dirichlet only applies to the multivariate version not the unidimensional version.

@aloctavodia aloctavodia merged commit 85c3d7d into arviz-devs:main Oct 8, 2024
1 check passed
@aleicazatti aleicazatti deleted the logitnormal branch October 9, 2024 18:04
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

2 participants