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<< Click to Display Table of Contents >> WEIBULL (Weibull distribution) |
Note: WEIBULL is supplemented by the new identical function WEIBULL.DIST, which is available in newer versions of Microsoft Excel (2010 or later).
Syntax:
WEIBULL(x, Alpha, Beta, Cumulative)
Description:
Returns the Weibull distribution function.
The Weibull distribution is an extension of the exponential distribution (see function EXPON.DIST/EXPONDIST) to occurrences that are not purely random and do not exactly match the Poisson distribution (see function POISSON.DIST/POISSON).
It is used especially for reliability analysis.
x is the value to be evaluated. Must be ≥ 0.
Alpha is a parameter of distribution. Alpha determines the shape of the distribution curve. If Alpha = 1, the Weibull distribution equals an exponential distribution with Lambda = 1/Beta.
Beta is another parameter of the distribution. Beta determines the scaling of the distribution curve, i.e. it stretches or compresses the function graph.
Both parameters has to be greater than zero.
The logical value Cumulative lets you specify which type of function will be returned:
FALSE: The probability density function is returned.
TRUE: The cumulative distribution function is returned.
Example:
WEIBULL(42, 2, 100, TRUE) returns 0.16172
WEIBULL(42, 2, 100, FALSE) returns 0.00704
See also: