Revision as of 15:28, 14 August 2013

Introduction

Random variables are useful for modeling uncertainty in a system. Unlike regular variable, which are defined by (deterministic) values, random variables are defined by distributions. Rave supports the use of random variables through various sampling (Monte Carlo) based approaches. The main ways to use random variables in Rave are:

• Declare a variable to be random, in which case it is treated as being random for all purposes in Rave.
• Sample data according to random distributions. This lets you generate a data set that involves randomness, but Rave otherwise treats this data as if it were a deterministic sampling.

In either case, Rave samples the random variables according to distributions that you define in Rave. The process of defining distributions is described below.

Note: only independent variables can be treated as random. Function variables become random when one or more of their input variables are random.

Defining and Modifying Distributions

Working with Random Variables

Method 1: Declaring a Variable to be Random

To declare a variable to be random, right click its column header in the main table and select Treat as a Random Variable. To indicate that a particular variable is random, its name in the main table column header turns purple, and its values in the table are replaced with the word "Random".

Method 2: Sampling Data from Distributions