In modelling and simulation, __________ is performed by comparing experiment…

CONCEPT: In Zeigler's Theory of Modeling and Simulation, a Real System, a Model, and a Simulator operate together within a specified Experimental Frame — the set of conditions, inputs, and observed variables that define the circumstances under which the system is studied. Two distinct checks establish trust in this framework: Verification confirms that the Simulator correctly executes the instructions of the Model (a Model-to-Simulator relation, with no real-world data involved), while Validation confirms that the Model's behaviour matches the actual behaviour of the Real System — judged by comparing real-system (experimental) measurements against the simulation's output, within that same Experimental Frame.

APPLICATION: The blank in this question describes exactly the second check: taking measurements gathered from experiments on the real system and comparing them with the results produced by the simulation, within the context of the Experimental Frame. That real-data-versus-simulated-data comparison is precisely how Validation is defined and carried out.

CROSS-CHECK — why the other terms don't fit:

• Verification checks whether the simulator correctly implements the model's own internal logic and specification — a Model-to-Simulator check that never compares against real-system experimental measurements.

• Testing is the broad software-engineering activity of exercising an implementation to uncover defects; it is not the specific modelling-and-simulation term for comparing real measurements against simulation output inside an Experimental Frame.

• Comparison names only the generic act of comparing two data sets; it is not itself a defined stage of the modelling-and-simulation lifecycle.