GAMMAINV function

Returns the inverse of the gamma cumulative distribution. If p = GAMMADIST(x,...), then GAMMAINV(p,...) = x.

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

Syntax

GAMMAINV(probability,alpha,beta)

Probability     is the probability associated with the gamma distribution.

Alpha     is a parameter to the distribution.

Beta     is a parameter to the distribution. If beta = 1, GAMMAINV returns the standard gamma distribution.

Remarks

  • If any argument is text, GAMMAINV returns the #VALUE! error value.

  • If probability < 0 or probability > 1, GAMMAINV returns the #NUM! error value.

  • If alpha ≤ 0 or if beta ≤ 0, GAMMAINV returns the #NUM! error value.

Given a value for probability, GAMMAINV seeks that value x such that GAMMADIST(x, alpha, beta, TRUE) = probability. Thus, precision of GAMMAINV depends on precision of GAMMADIST. GAMMAINV 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

    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.

1

2

3

4

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)

=GAMMAINV(A2,A3,A4)

Inverse of the gamma cumulative distribution for the above terms (10.00001131)

Applies To: Excel 2007



Was this information helpful?

Yes No

How can we improve it?

255 characters remaining

To protect your privacy, please do not include contact information in your feedback. Review our privacy policy.

Thank you for your feedback!

Support resources

Change language