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.

How to copy an example

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

   Note Do not select the row or column headers.

   Selecting an example from Help

3. Press CTRL+C.
4. In the worksheet, select cell A1, and press CTRL+V.
5. 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.

See also:

• BETADIST
• Statistical functions