Dirichlet Distribution
Explore a continuous probability simplex, Dirichlet concentration, exact count-based Bayesian updates and uncertainty over category probabilities.
Free theory articleExplore a continuous probability simplex, Dirichlet concentration, exact count-based Bayesian updates and uncertainty over category probabilities.
Concept & interpretation
A multinomial model counts outcomes when category probabilities are fixed. A Dirichlet model expresses uncertainty about those probabilities themselves. Here P = (PA, PB, PC) is a continuous random vector. Its components are nonnegative and sum to one, so its possible values form a triangle called the probability simplex.