GAMMAINV

See Also

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

GAMMAINV uses an iterative technique for calculating the function. Given a probability value, GAMMAINV iterates until the result is accurate to within ±3x10^-7. If GAMMAINV does not converge 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 spreadsheet.

How?

  1. Create a blank spreadsheet.
  2. Select the example in the Help topic.

    Selecting example from Help

    Selecting an example from Help

  3. Press CTRL+C.
  4. In the spreadsheet, select cell A1, and press CTRL+V.
  5. To switch between viewing the formula that returns the result and the result in the cell, select the cell and press F2 and then ENTER, or click Commands and Options on the spreadsheet toolbar, click the Formula tab, and look in the Formula in active cell (active cell) box.
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)