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Statistical - WEIBULL.DIST Function
Description
The WEBULL.DIST function returns the Weibull distribution. Use this distribution in reliability analysis, such as calculating a device's mean time to failure.
Syntax
WEIBULL.DIST(x,alpha,beta,cumulative)
Arguments
Argument | Description | Required/Optional |
---|---|---|
X | The value at which to evaluate the function. | Required |
Alpha | A parameter to the distribution. | Required |
Beta | A parameter to the distribution. | Required |
Cumulative | Determines the form of the function. | Required |
Notes
The equation for the Weibull cumulative distribution function is −
$$F\left ( x;\alpha ,\beta \right )=1-e^{-\left ( X/\beta \right ) ^\alpha}$$
The equation for the Weibull probability density function is −
$$F\left ( x;\alpha ,\beta \right )=\frac{\alpha }{\beta^a }x^{a-1}e^{\left ( -x/\beta \right )^\alpha }$$
When alpha = 1, WEIBULL.DIST returns the exponential distribution with −
$$\lambda =\frac{1}{\beta }$$
If x, alpha, or beta is nonnumeric, WEIBULL.DIST returns the #VALUE! error value.
If x < 0, WEIBULL.DIST returns the #NUM! error value.
If alpha ≤ 0 or if beta ≤ 0, WEIBULL.DIST returns the #NUM! error value.
Applicability
Excel 2010, Excel 2013, Excel 2016