System Dynamics Applications / 6

6 VERIFICATION AND VALIDATION

6.1 VERIFICATION—BUILDING THE MODEL RIGHT

Two essential model-building activities are verification and validation. Unfortunately these two terms are often used interchangeably, which leads to confusion. Verification and validation involve two distinctly different types of activities but which are inseparable when it comes to system dynamics modelling.

For our purposes, verification can be defined as (Jones, 1996: 94-96; Rakitin, 1997: 51-66):

The process of determining whether or not the products of a given phase of the system dynamics modelling development cycle fulfil the requirements established during the previous phase.

Another way to view verification activities is that verification helps us answer the question: “Are we building the model right?’

In system dynamics modelling, verification is all about ensuring that the governing business rules have been correctly coded, that the structure in which those rules operate results in correct replication of the reference modes of behaviour identified in an earlier stage (and specified as requirements for the model we are building).