WorksheetFunction.Gamma_Inv (Excel)

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

You can use this function to study a variable whose distribution may be skewed. 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 100 iterations, the function returns the #N/A error value.

Gamma_Inv (Arg1, Arg2, Arg3)

Dim dblArg1 As Double: dblArg1 = 
Dim dblArg2 As Double: dblArg2 = 
Dim dblArg3 As Double: dblArg3 = 
Dim dblGamma_Inv As Double
dblGamma_Inv = WorksheetFunction.Gamma_Inv(Arg1:=dblArg1, Arg2:=dblArg2, Arg3:=dblArg3)

Arguments

Arg1 (Double) - Probability - the probability associated with the gamma distribution.

Arg2 (Double) - Alpha - a parameter to the distribution.

Arg3 (Double) - Beta - a parameter to the distribution. If beta = 1, Gamma_Inv returns the standard gamma distribution.