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# WorksheetFunction.Beta_Inv Method (Excel)

Office 2013

Published: July 16, 2012

Returns the inverse of the cumulative distribution function for a specified beta distribution. That is, if probability = Beta_Dist(x,...), then Beta_Inv(probability,...) = x.

expression .Beta_Inv(Arg1, Arg2, Arg3, Arg4, Arg5)

expression A variable that represents a WorksheetFunction object.

### Parameters

Name

Required/Optional

Data Type

Description

Arg1

Required

Double

A probability associated with the beta distribution.

Arg2

Required

Double

The Alpha parameter of the distribution.

Arg3

Required

Double

The Beta parameter the distribution.

Arg4

Optional

Variant

An optional lower bound to the interval of x.

Arg5

Optional

Variant

An optional upper bound to the interval of x.

### Return Value

Double

The beta distribution can be used in project planning to model probable completion times given an expected completion time and variability:

• If any argument is nonnumeric, Beta_Inv generates an error value.

• If alpha ≤ 0 or beta ≤ 0, Beta_Inv generates an error value.

• If probability ≤ 0 or probability > 1, Beta_Inv generates an error value.

• If you omit values for A and B (lower and upper bound), Beta_Inv uses the standard cumulative beta distribution, so that A = 0 and B = 1.

Given a value for probability, Beta_Inv seeks that value x such that Beta_Dist(x, alpha, beta, TRUE, A, B) = probability. Thus, precision of Beta_Inv depends on precision of Beta_Dist. Beta_Inv uses an iterative search technique.