Statistics 简明教程

Statistics - Beta Distribution

The beta distribution represents continuous probability distribution parametrized by two positive shape parameters, $ \alpha $ and $ \beta $, which appear as exponents of the random variable x and control the shape of the distribution.

beta distribution

Probability density function

Probability density function of Beta distribution is given as:

Formula

其中——

  1. ${ \alpha, \beta }$ = shape parameters.

  2. ${a, b}$ = upper and lower bounds.

  3. ${B(\alpha,\beta)}$ = Beta function.

Standard Beta Distribution

In case of having upper and lower bounds as 1 and 0, beta distribution is called the standard beta distribution. It is driven by following formula:

Formula

Cumulative distribution function

Cumulative distribution function of Beta distribution is given as:

Formula

其中——

  1. ${ \alpha, \beta }$ = shape parameters.

  2. ${a, b}$ = upper and lower bounds.

  3. ${B(\alpha,\beta)}$ = Beta function.

It is also called incomplete beta function ratio.