How to use GAMMA.DIST Function in Excel

The GAMMA.DIST function returns the gamma distribution. You can use this function to study variables that may have a skewed distribution. The gamma distribution is commonly used in queuing analysis.

Syntax:= GAMMADIST(x,alpha,beta,cumulative)

The GAMMA.DIST function syntax has the following arguments:

  • X     Required. The value at which you want to evaluate the distribution.
  • Alpha     Required. A parameter to the distribution.
  • Beta     Required. A parameter to the distribution. If beta = 1, GAMMA.DIST returns the standard gamma distribution.
  • Cumulative     Required. A logical value that determines the form of the function. If cumulative is TRUE, GAMMA.DIST returns the cumulative distribution function; if FALSE, it returns the probability density function.

Example: Let’s look at some Excel GAMMA.DIST function examples and explore how to use the GAMMA.DIST function as a worksheet function in Microsoft Excel:

GAMMA.DIST Function 2 - How to use GAMMA.DIST Function in Excel

Syntax:  =GAMMA.DIST(B1,B2,B3,FALSE)

Result: 0.112020904

GAMMA.DIST Function 1 - How to use GAMMA.DIST Function in Excel

Based on the Excel spreadsheet above, the following GAMMA.DIST examples would return:

Syntax: =GAMMA.DIST(B1,B2,B3,FALSE)
Result: 0.112020904

Syntax: =GAMMA.DIST(B1,B2,B3,TRUE)
Result: 0.576809919

Note:

  • If x, alpha, or beta is nonnumeric, GAMMA.DIST returns the #VALUE! error value.
  • If x < 0, GAMMA.DIST returns the #NUM! error value.
  • If alpha ≤ 0 or if beta ≤ 0, GAMMA.DIST returns the #NUM! error value.
  • The equation for the gamma probability density function is:
    GAMMA.DIST Function in Excel - How to use GAMMA.DIST Function in Excel
    The standard gamma probability density function is:
    GAMMA.DIST Function in Excel 1 - How to use GAMMA.DIST Function in Excel

  • When alpha = 1, GAMMADIST returns the exponential distribution with: GAMMA.DIST Function in Excel 3 - How to use GAMMA.DIST Function in Excel
  • For a positive integer n, when alpha = n/2, beta = 2, and cumulative = TRUE, GAMMA.DIST returns (1 – CHISQ.DIST.RT(x)) with n degrees of freedom.
  • When alpha is a positive integer, GAMMA.DIST is also known as the Erlang distribution.

 

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