Definition:Uniform Distribution/Discrete

Definition
Let $X$ be a discrete random variable on a probability space.

Then $X$ has a discrete uniform distribution with parameter $n$ if:


 * $\Img X = \set {1, 2, \ldots, n}$


 * $\map \Pr {X = k} = \dfrac 1 n$

That is, there is a number of outcomes with an equal probability of occurrence.

This is written:
 * $X \sim \DiscreteUniform n$

This distribution trivially gives rise to a probability mass function satisfying $\map \Pr \Omega = 1$, because:
 * $\displaystyle \sum_{k \mathop \in \Omega_X} \frac 1 n = \sum_{k \mathop = 1}^n \frac 1 n = n \frac 1 n = 1$

Thus it serves as a model for a discrete probability space with equiprobable outcomes.

Also see

 * Definition:Continuous Uniform Distribution