Re: Simulating Individual B

[Randall Gray]

ABM's do indeed pose some problems w.r.t. "calibration".  In a project
of days gone by we skirted the issue somewhat by attempting to
"bracket" reality in our range of assumptions of behaviour.  We were
looking at potential contamination of a marine trophic chain due to
period (regular) dumping of a low level hazardous waste at sea.  We
ran a range of models which went from the most pessimistic to quite
optimistic in terms of behaviour with respect to tainted waters and
assessed the results.  I am certain that what we did was not optimal,
but collecting the sort of data we'd have required would have been
(and still is) prohibitively expensive.

I suppose the issue is "How close to reality do we need to get before
the simulation exhibits the same sorts of strange attractors or
ritical modes we see in Real Life?"  Moreover, how do we correctly
identify that we've arrived?

I suppose that the problem with the ecosystem work is that you may
only see a few critical modes in an ecosystem under study, but with
your simulation you might actually come across dozens more.  Some of
the strange attractors arise from the implementation of the model,
some are critical modes of the simulation, and some are also critical
modes of the system being simulated.  You always *hope* that the
strange attractors of the system are strange enough to raise your
suspicions, but differentiating the other two seems to be one of those
harder problems.

-- Randall



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