Dan is right on the money
Plus the fact that the best fit between climate data and simulated
data is with the average output from the best *six*! or so models they
run, not with any one single model.
Finallu, there is no explanation--much less theory--as to why this
trick works. Think about it ;-)
Sent from my iPhone
On Apr 29, 2009, at 10:37 AM, Dan Olner <[log in to unmask]> wrote:
> Hi,
>
> No references, sorry, just a question. If one were to ask
> metereologists to present evidence that they produced correct
> forecasts, what would be acceptable? How would that differ from what
> we might consider acceptable for economic or policy forecasting?
>
> At a recent talk by a metereologist I was struck by a) the fact that
> everyone from the military to someone walking kids to school relies
> on their forecasts but that b) it's as complex a system as you could
> hope for. One way they deal with this is through producing a broad
> range of thumbnail predictions given slightly different starting
> parameters - the job of interpretation of these is then a human one.
>
> I think it's a useful comparison: no-one expects metereology to give
> anything but broad brushstroke predictions, because of the nature of
> the system they model. After about 7 days out, all bets are off -
> though some boundary conditions can be predicted for long-range
> forecasts. (and with e.g. climate change.) The question then is:
> what do are we willing to accept as a useful set of predictions
> (rather than strictly correct.)
>
> Clearly, what's valid in metereology probably won't be for other
> forms of modelling. Interestingly, though, the person giving the
> talk told me they don't even like to talk about validation. I'd like
> to find out more about that, given how obsessively everyone in agent-
> based modelling is pursuing this enigmatic beast.
>
> Anyway, my point was: one could ask metereologists to hand over
> examples of correct forecasts, and they could do this - since
> forecasts are right at least some of the time. But the more
> appropriate question is whether they did better than pulling
> forecasts out of a hat.
>
> Got some more thoughts on this but gotta go...
>
> Cheers,
>
> Dan
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