Well Ben, isn't that the trouble with models? We have to assume good faith
on the part of whomever developed the model or is using it. That may be OK
in some cases, but it isn't good science. A few years ago "null hypothesis"
models were all the rage in ecology. However, in most cases the actual data,
when compared to the model, turned out to be no different from random
chance. In other words, the model seemed to be saying that there were no
"real" ecological relationships in nature, that all was just random
associations. So, was the problem with nature, the model, or the modelers?
Steven
“Our human ecology is that of a rare species of mammal in a social,
omnivorous niche. Our demography is one of a slow-breeding, large,
intelligent primate. To shatter our population structure, to become abundant
in the way of rodents, not only destroys our ecological relations with the
rest of nature, it sets the stage for our mass insanity.”
Paul Shepard
-----Original Message-----
From: Discussion forum for environmental ethics.
[mailto:[log in to unmask]]On Behalf Of Benjamin S Hale
Sent: Monday, December 18, 2000 12:16 PM
To: [log in to unmask]
Subject: Re: Models of global warming
>
> Funny, I don't see anything about looking to see if perhaps the model is
> indeed Bravo Sierra. I can get a good fit with any regression model by
> simply exhausting the degrees of freedom. That is, if I keep putting in
> enough variables (especially lags of the dependent variable) I can get a
> great fit to the data. However, there is nothing to ensure the
> predicitive power of the model.
>
Ya' know, to a certain degree, you're absolutely right -- you can pretty
much get any regression model to fit any data set. On the other hand,
perhaps we should assume that the scientists and modellers are using a
little bit of Ockham's razor in coming up with the best possible -- though
simplified -- explanation of the data. I don't know what kind of skeptic
you want to be here, but it seems naive to argue that just because there
is "some doubt" in the model, that we ought to go the length to
say that it is "shot through with doubt" and discard it. I think it far
more conservative to presume that the folks running these regressions were
smart enough not to be too lax with the degrees of freedom, and that since
entire boatloads of people seem to think this model a feasible explanation
of the data, that perhaps we ought to heed some of its predictions.
Ben
|