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title: "Weibull"
canonical: "https://modelassist.epixanalytics.com/space/EA/26575257/Weibull"
format: markdown
---
Weibull(Location,Scale,Shape), usually Weibull(0,*b*,*a)*

[Weibull equations](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26576473)

[Crystal Ball parameter restrictions](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26575280/)

 

 

 

Examples of the Weibull distribution are given below:

 

![image](media://8c9df2fa-29f0-4248-a767-e39145348f55)

 

#### Uses

The Weibull distribution is often used to [model the time until occurrence of an event](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26575632/) where the probability of occurrence changes with time (the process has "memory"), as opposed to the [Exponential distribution](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26575227/) where the probability of occurrence remains constant ("memoryless"). It has also been used to model variation in wind speed at a specific site. Example: [Light bulbs](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26575628/).

#### Comments

The Weibull distribution becomes an exponential distribution when *a* = 1, i.e. Weibull(0,*b,1*) = Exponential(1/*b*). The Weibull distribution is very close to the [Normal](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26575246/) distribution when *b* = 3.25. The Weibull distribution is named after the Swedish physicist Dr E. H. Wallodi Weibull (1887-1979)  who used it to model the distribution of the breaking strengths of materials.

 

The Excel function [WEIBULL](https://epixanalytics.atlassian.net/wiki/spaces/EA/pages/26575257/)(x,*a*,*b*,**0**) returns the probability density function for the Weibull(0,b,a) distribution, while WEIBULL(x,*a*,*b*,**1**) returns its cumulative distribution function.

 

 

 

 

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