.
| Modeling: | move from the real world of troubles
into the world of unsolved but solvable puzzles |
| Application: | move from the world of solved puzzles
into the world of troubles and real actions to deal with them |
Sometimes application can be very simple and straightforward: the optimal output numbers of mathematical programming or the most successful input numbers of simulation become volts, hours, or dollars in the real world, the optimal choice in decision analysis becomes a signature on a contract, and the projection of a forecasting model is treated as a peek into the future.
Much more often, the responsible human managers use a process of reasoning by analogy to gain insights about the real world that go far beyond slavishly copying computer outputs.
The more we take into consideration the approximations and uncertainties in the modeling process, the more insight we can gain during the application phase.
Directly or indirectly, the application phase results in a plan of action, which in this imperfect world will more than likely eventuate in new troubles, so the process continues.