Modeling and simulation is the practice of building a model of a system and running that model to see how the system would behave. The model is a simplified stand-in. A run of the model is the simulation. The point is to learn from the run without having to disturb the real system every time.
When a person stays inside that run, the setup is Human-In-The-Loop (HITL). The model advances, the person acts, and the model responds to the action. A run with no person in it is a different setup.
What a Useful Model Has to Keep
- The behavior under study. The model includes the parts that can change the result, and leaves out the rest.
- A way to start it. Inputs are set, and the run proceeds from those inputs.
- A result that can be compared. The output is something the real system also produces, so the model can be checked.
A Run with a Person and a Run Without One
| Compared | A Person Inside the Run | No Person Inside the Run |
| Who decides the next action | The person, seeing the current state | The model’s own rules |
| What is being learned | How a person and the system affect each other | How the system behaves on its own |
| Repeating the run | The person may choose differently | The same inputs give the same path |
