BETAINV ( probability , alpha , beta [ , [ A ] , [ B ] ] )

Description: Computes the inverse of the cumulative distribution function for a specified beta distribution. Given a value for probability, BETAINV is used to seek for the value x such that BETADIST(x, alpha, beta, A, B) = probability. Thus, precision of BETAINV depends on precision of BETADIST. BETAINV uses an iterative search technique.

Arguments:

Name	Type	Description
probability	number	A probability associated with the beta distribution.
alpha	number	A parameter of the distribution.
beta	number	A parameter of the distribution.
A	number	The lower bound to the interval of x. If omitted, the lower bound is 0.
B	number	The upper bound to the interval of x. If omitted, the upper bound is 1.

Return Type and Value: number – The inverse of the cumulative distribution function for a specified beta distribution.

However, if

• alpha or beta ≤ 0, #NUM! is returned.

• probability < 0 or probability > 1, #NUM! is returned.

• The search has not converged after some implementation-defined number of iterations, #N/A is returned.

[Example:

BETAINV(0.5,1,2) results in 0.29289341
BETAINV(0.5,1,2,-4.5,7.3) results in -1.043857765
BETAINV(0.5,1,2,,2.3) results in 0.673654842

end example]