Naively, should the simulation work well and teach lessons in management
of the world economy to those looking for that data, how will the
simulation recursively model itself within it own simulation? It must be
an unknown quantity, no? As the results of its model produce unknown
outputs which cannot be input to the model before it is run? I know
this is a theoretical rather than practical question, as one can
perfectly well produce models of country or economic behaviour which
function perfectly well in providing a gross predictivity as to
outcomes. However, should these be scaled to the global level and the
assumption of success be made, it seems destined to become a problem.
pete wrote:
>
> (A glitch on my dial-in just caused mail to be sent out with this
> title
> but no body. this is the post which was intended...)
>
> "Douglas P. Wilson" <[EMAIL PROTECTED]> wrote:
>
> >I'd like to write a program to run a simulation of the world economy,
> >first to see if Jay's conclusions follow from his own data, and then
> >to do a sensitivity analysis to see what are the most important
> >variables.
> >
> >I propose to put this program up on the web in source code form as
> >well as compiled binaries, so that everyone can check to see how
> >plausible the model is, and can play with it a bit.
>
> >I do have some expertise in this area, having worked on a simulation
> >of the Canadian air traffic control system in Ottawa a while back,
> but
> >by putting actual source code up on the web I hope to minimize the
> >dependence of the model on my own personal expertise.
> >
> >To do this, I will need some data, and I hope Jay will be willing to
> >provide the data underlying his own conclusions.
> >
> >This is just an idea at the moment, but it sounds like a worthwhile
> >project, consistent with my often stated preference for algorithms
> >over arguments, and I don't think it will too difficult. What do you
> >think?
>
> This is an approach I have advocated for a long time, so of course
> I'm all in favour. However there are some important points to make:
> a proper simulation is not a trivial project; I had envisioned it
> being the product of a team effort in the order of several man-years.
> Most importantly, the simulation will be of no value if it is
> algorithm-driven. To reflect the true picture, it must be an FSA
> (Finite State Automata) model. Algorithms may be deduced from its
> results, but not ordained in its construction. The simulation should
> model the actions of individual players, and be iterated over cohorts
> over time. A well constructed simulation should be able to model
> any form of economy one can imagine, and not be limited by the
> constrictive assumptions built into an algorithm-driven simulation.
>
> By the way, algorithm-based simulations already exist, and are used
> regularly by economists, which should be a clear demonstration that
> they are no damn good. To see an example, check out the International
> Futures model which I believe can still be found at IFS.org.
>
> -Pete Vincent
--
Mark Measday
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