﻿ BETAINV function

# BETAINV function

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.

Important   This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. This function is still available for compatibility with earlier versions of Excel. However, if backward compatibility is not required, you should consider using the new functions from now on, because they more accurately describe their functionality.

## Syntax

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

The BETAINV function syntax has the following arguments:

• Probability     Required. A probability associated with the beta distribution.

• Alpha     Required. A parameter of the distribution.

• Beta     Required. A parameter the distribution.

• A     Optional. A lower bound to the interval of x.

• B     Optional. An 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.

## Example

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

How do I copy an example?

Important   Do not select the row or column headers.

Selecting an example from Help

2. Press CTRL+C.

3. In Excel, create a blank workbook or worksheet.

4. In the worksheet, select cell A1, and press CTRL+V.

Important   For the example to work properly, you must paste it into cell A1 of the worksheet.

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.

After you copy the example to a blank worksheet, you can adapt it to suit your needs.

 1 2 3 4 5 6 7 8
 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 2010, Excel Starter, SharePoint Online, Excel Online

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