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 nonnumeric, 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?- Create a blank workbook or worksheet.
- Select the example in the Help topic. Do not select the row or column headers.
Selecting an example from Help
- Press CTRL+C.
- In the worksheet, select cell A1, and press CTRL+V.
- To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Tools menu, point to Formula Auditing, and then click Formula Auditing Mode.
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