One feature that sets FlexSim apart from other simulation tools is the ability to quickly and easily build a little bit of variability and randomness into your simulation model. FlexSim gives you the ability to simulate many kinds of fluctuations in your business system. Fortunately, you don't need to know a lot of complicated mathematics or programming to create these mathematical expressions. FlexSim has a tool called the Distribution Chooser that will help you select an appropriate statistical distribution to randomly calculate any kind of randomness. When you're done using the Distribution Chooser, it will create a mathematical expression based on the options you selected and it will automatically apply it to the daily demand or process times settings.
The Distribution Chooser is shown in the following image:
The Distribution Chooser allows you to select from thirty possible statistical distributions to generate random numbers. See Commonly Used Statistical Distributions for an overview of some of the frequently used distributions.
You can change the settings for each statistical distribution so that it uses different criteria or ranges of numbers to generate the random numbers. When you make changes to the settings, the blue bar graph will update to display the probabilities that certain numbers will be generated.
Many object properties are capable of using a statistical distribution. To use the Distribution Chooser for these properties:
For more information about some of the different distributions and their parameters, read the next topics in this section.
Some of the most commonly used distributions are:
Each of these distributions will be discussed in more detail in the following sections.
The Exponential distribution will randomly select most numbers near the beginning of a range of numbers. The frequency that numbers near the end of the scale will be generated decreases exponentially. This is the default distribution strategy because it is the distribution strategy most commonly found in the real world. The following image shows an example of the Exponential distribution strategy:
The Exponential distribution has three settings:
When you make changes to the settings, the blue bar graph will update to display the probabilities that certain numbers will be generated. Usually, the bar graph doesn't change much for the Exponential distribution, but the range of the numbers listed on the bottom of the graph will change.
The Duniform distribution will randomly select numbers within a specific range. If you want to be able to include numbers with decimal points, use the Uniform distribution strategy instead. The following image shows an example of the Duniform distribution strategy:
The Duniform distribution has three settings:
The Normal distribution has a distribution strategy similar to a bell curve in which numbers in the middle of the distribution scale are more likely to be generated at random, as shown in the following image:
The Normal distribution has three settings:
The Triangular distribution is similar to the normal distribution strategy, but has a greater range of numbers in the middle of the distribution scale that are more likely to be generated at random, as shown in the following image:
The Triangular distribution has four settings:
The Uniform distribution will randomly select numbers within a specific range. The uniform distribution strategy will include numbers with decimal points. If you'd rather only create whole numbers, use the Duniform distribution strategy instead. The following image shows an example of the Uniform distribution strategy:
The Uniform distribution has three settings: