# GAMMA.INV function

Returns the inverse of the gamma cumulative distribution. If p = GAMMA.DIST(x,...), then GAMMA.INV(p,...) = x.

You can use this function to study a variable whose distribution may be skewed.

## Syntax

`GAMMA.INV(probability,alpha,beta)`

The GAMMA.INV function syntax has the following arguments (argument: A value that provides information to an action, an event, a method, a property, a function, or a procedure.):

• Probability     Required. The probability associated with the gamma distribution.
• Alpha     Required. A parameter to the distribution.
• Beta     Required. A parameter to the distribution. If beta = 1, GAMMA.INV returns the standard gamma distribution.

## Remarks

• If any argument is text, GAMMA.INV returns the #VALUE! error value.
• If probability < 0 or probability > 1, GAMMA.INV returns the #NUM! error value.
• If alpha ≤ 0 or if beta ≤ 0, GAMMA.INV returns the #NUM! error value.

Given a value for probability, GAMMA.INV seeks that value x such that GAMMA.DIST(x, alpha, beta, TRUE) = probability. Thus, precision of GAMMA.INV depends on precision of GAMMA.DIST. GAMMA.INV uses an iterative search technique. If the search has not converged after 64 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.

1. Select the example in this article. If you are copying the example in Excel Web App, copy and paste one cell at a time.Important Do not select the row or column headers.

Selecting an example from Help

1. Press CTRL+C.
2. Create a blank workbook or worksheet.
3. In the worksheet, select cell A1, and press CTRL+V. If you are working in Excel Web App, repeat copying and pasting for each cell in the example.

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

1. 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.

A B
Data Description
0.068094 Probability associated with the gamma distribution
9 Alpha parameter to the distribution
2 Beta parameter to the distribution
Formula Description (Result)
=GAMMA.INV(A2,A3,A4) Inverse of the gamma cumulative distribution for the above terms (10.00001131)

Applies to:
Excel 2010, Excel Web App, SharePoint Online for enterprises, SharePoint Online for professionals and small businesses