Part 2. MM4XL Tools > 1. Strategic Tools > Risk Analyst > 4. Functions > 3. Distribution Functions > mmWEIBULL(Life, Shape)

Risk Analyst

mmWEIBULL(Life, Shape)


=mmWEIBULL(1, 5) can equal 0.661022544.


This is a distribution often used to model failure time (lifetime expectancy), fatigue and fracture, as well as distributions of physical quantities, such as wind speed. Some authors mention the employment of the Weibull distribution to model the years to failure for a business.

How to use

Say our company distributes sodas through dispensers placed in crowded areas. On average, after 90 hours a machine needs maintenance. Without maintenance the machine stops working and must be reset before being put back in service, which carries higher costs. We are modeling a project to decide whether to increase the number of machines or not. The formula below can help to model the time when a machine enters the critical time for maintenance:

=mmWEIBULL(1.3, 93)

The chart below shows that 61.7% of the machines of our example will require maintenance within 90 hours.

 Monte Carlo Simulation Software: Management Process Risk Analysis

Attributing the correct values for Life and Shape, the parameters of the Weibull distribution, is not always easy. We suggest you use the Fit data option available in Risk Analyst in order to estimate reasonable parameters from existing data.

Technical profile

Type Continuous distribution.
Syntax =mmWEIBULL(Life, Shape)
Domain  Monte Carlo Simulation Software: Management Process Risk Analysis; generates positive numbers only
Mode If Shape >= 1 then =
If Shape <= 1 then = 0
Parameters Life = b > 0
Shape = c > 0
Remarks If any argument is nonnumeric mmWEIBULL returns the #VALUE! error value.
Relationships It is related to the Exponential, Rayleigh and Extreme Value variate.
mmWEIBULL(1, 5) mmWEIBULL(10, 5)
 Monte Carlo Simulation Software: Management Process Risk Analysis  Monte Carlo Simulation Software: Management Process Risk Analysis
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Price: euro 238.00

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