Unrealistic proposal requests

Besides software development, my responsibilities also include assessing and answering simulation related proposal requests from other firms. Since simulation is usually poorly understood, the requester puts in sentences like "the simulation shall be realistic" without knowing how vague and overly ambitious that is.

Without going into philosphical details about what is "realistic", I can say that it involves a lot of real world testing and modeling. The budget that is available is usually less than 1% needed to fulfill realism. In that case we have two choices:

1. Prepare a proposal that takes every possible risk into account and demand a billion dollars (same as saying NO).
2. Think about what can be done with the given budget, write down your assumptions and limitations and present that as a proposal. This is the way to go if you want to avoid suffering.

The major cost factor in a simulation project is integration and testing. Your first question to any proposal request should be "how will you know that our simulation works as you expect". The answer will determine not only how much testing is needed but also how detailed your models should be. It is like unit tests driving design. If you don't get a satisfactory answer, write down in your proposal how and where you will test it.