[ScottBurson]

> isn't the code just a language/stack/programmer(s) specific interpretation of the underlying model?

There's the catch -- it should be, but there's no way to verify it's correct without comparing the source code against the model. (Well, I suppose if you had access to the raw data and the time to rewrite the software yourself from scratch, you could do that and see if you got the same results. But who has time for that?)

[marvy]

I don't know who has time for that, but it's far more reliable than auditing source code. Two people using two different languages are not likely to code up the same bug, but overlooking a bug in code someone else wrote is easy. Besides, coding things up yourself is not much slower than a full audit: understanding other people's code is hard. There's a reason that many developers have an urge to throw out "legacy" code and redo it from scratch.