System walkthrough
Explaining model to another person/persons – enables modeller to focus on different aspects and to discover problems.
Writing system documentation can have the same effect to by making to modeller look at model from different perspective.
Consistency testing
Check model produces similar results for input parameter values that have similar effects.
Example: Network with two inputs, each with arrival rates of 100 packets/sec. Should cause approximately same amount of traffic as four inputs each with 50 packets/sec.
If model shows discrepancy then it should be explainable with more detailed knowledge of the system. If not, then they could be an error.