I can point you to one or two things of interest. In modeling differential equations, there is an entire field of inquiry entitled "sensitivity analysis". The idea there is to compute derivatives of outputs with respect to various inputs, all dependent on the DE's governing the system. That field can quantify to some extent the possible errors introduced by what are, essentially, fractals (surface area computed by somehow integrating around each molecule, for instance!).
One other source I am aware of is the dependence of solutions on initial conditions in the field of ODE's. This has been handled in Coddington and Levinson (as, in fact, many things have been handled!).
Although it sounds like you're more interested in extensive changes to a model, you might also check out perturbation theory.
Hope this is at least somewhat helpful. I, alas, know very little about any of these fields, so this is as much as I can say, pretty much. Good luck!