The Excel WEIBULL.DIST function calculates the Weibull Probability Density Function or the Weibull Cumulative Distribution Function for a supplied set of parameters. Although the function is new in Excel 2010, it is simply a renamed version of the Weibull function, which is available in Excel 2007 and earlier.
Syntax: WEIBULL.DIST( x, alpha, beta, cumulative )
|x||–||The value at which the function is to be calculated (must be ≥ 0)|
|alpha||–||The Shape parameter to the distribution (must be > 0)|
|beta||–||The Scale parameter to the distribution (must be > 0)|
|cumulative||–||A logical argument which denotes the type of distribution to be used;
Weibull.Dist Function Examples
|Example 1 – Weibull Probability Density Function
The chart on the right shows the Weibull Probability Density Function with the shape parameter, α = 3 and the scale parameter, β = 1.
If you want to calculate the value of this function at x = 1, this can be done with the Weibull.Dist function, as follows:
=WEIBULL.DIST( 1, 3, 1, FALSE )
This gives the result 1.10363832351433.
|Weibull Probability Density Function with α = 3 and β = 1|
|Example 2 – Weibull Cumulative Distribution Function
The chart on the right shows the the Weibull Cumulative Distribution Function with the shape parameter, α = 5 and the scale parameter, β = 1.5.
If you want to calculate the value of this function at x = 2, this can be done with the Weibull.Dist function, as follows:
=WEIBULL.DIST( 2, 5, 1.5, TRUE )
This gives the result 0.985212776817482.
|Weibull Cumulative Distribution Function with α = 5 and β = 1.5|
Weibull.Dist Function Errors
If you get an error from the Excel Weibull.Dist function this is likely to be one of the following :
|#NUM!||–||Occurs if either the supplied x value is < 0 or the supplied alpha or the supplied beta argument is ≤ 0|
|#VALUE!||–||Occurs when either of the supplied alpha or beta arguments are non-numeric|