Chapter 3 Probability Basics

Our final aim is to be able to mimic real-world systems as close as possible. In most scenarios we will not know with certainty how things unfold. For instance, we will rarely know the times at which customers enter a shop or the time it will take an employee to complete a task. Let’s think again at the donut shop example. The time it takes an employee to serve a costumer depends on the time it takes the customer to specify the order, the number and types of donuts requested, the type of payment etc. To an external observer all these possible causes of variation of serving times appear to be random and due to chance: they cannot be predicted with certainty.

For this reason we will in general assume a probabilistic model for the various components of a simulation. This chapter gives a review of possible models as well as their characteristics.