GAMMAINV

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.
• If beta £ 0, GAMMAINV returns the #NUM! error value.
• 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

GAMMAINV(0.068094,9,2) equals 10