BETAINV

Returns the inverse of the cumulative beta probability density function for a specified beta distribution. That is, if probability = BETADIST(x,...), then BETAINV(probability,...) = x. The beta distribution can be used in project planning to model probable completion times given an expected completion time and variability.

Syntax

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

Probability     is a probability associated with the beta distribution.

Alpha     is a parameter of the distribution.

Beta     is a parameter the distribution.

A     is an optional lower bound to the interval of x.

B     is an optional upper bound to the interval of x.

Remarks

• If any argument is nonnumeric, BETAINV returns the #VALUE! error value.
• If alpha ≤ 0 or beta ≤ 0, BETAINV returns the #NUM! error value.
• If probability ≤ 0 or probability > 1, BETAINV returns the #NUM! error value.
• If you omit values for A and B, BETAINV uses the standard cumulative beta distribution, so that A = 0 and B = 1.

Given a value for probability, BETAINV seeks that 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. If the search has not converged after 100 iterations, the function returns the #N/A error value.

Example

The example may be easier to understand if you copy it to a blank worksheet.

• Create a blank workbook or worksheet.
• Select the example in the Help topic.

Note   Do not select the row or column headers.

Selecting an example from Help
• Press CTRL+C.
• In the worksheet, select cell A1, and press CTRL+V.
• To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
A B
Data Description
0.685470581 Probability associated with the beta distribution
8 Parameter of the distribution
10 Parameter of the distribution
1 Lower bound
3 Upper bound
Formula Description (Result)
=BETAINV(A2,A3,A4,A5,A6) Inverse of the cumulative beta probability density function for the parameters above (2)

Applies to:
Excel 2003