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betastat

Beta mean and variance

Syntax

[M,V] = betastat(A,B)

Description

[M,V] = betastat(A,B), with A>0 and B>0, returns the mean of and variance for the beta distribution with parameters specified by A and B. A and B can be vectors, matrices, or multidimensional arrays that have the same size, which is also the size of M and V. A scalar input for A or B is expanded to a constant array with the same dimensions as the other input.

The mean of the beta distribution with parameters a and b is a/(a+b) and the variance is

ab(a+b+1)(a+b)2

Examples

If parameters a and b are equal, the mean is 1/2.

a = 1:6;
[m,v] = betastat(a,a)
m =
  0.5000  0.5000  0.5000  0.5000  0.5000  0.5000
v =
  0.0833  0.0500  0.0357  0.0278  0.0227  0.0192

Introduced before R2006a

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