I have now had half a dozen responses to my question about policy
forecasts but none seem to me to provide examples of what I had
_intended_ as the issue. I must have been unclear. Forgive me if I now
expatiate on the question.
The motivation for the question: In relation to policy, it is common
for social scientists (including but not exclusively economists) to use
some a priori reasoning (frequently driven by a theory) to propose
specific policies or to evaluate the benefits of alternative policies.
In either case, the presumption must be that the benefits or relative
benefits of the specified policies can be forecast. I am not aware of
any successful tests of this presumption and none of my colleagues at
the meeting of UK agent-based modelling experts could point me to a
successful test in the sense of a well documented correct forecast of
any policy benefit.
The importance of the question: If there is no history or, more weakly,
no systematic history of successful forecasts of policy impacts, then is
the standard approach to theory-driven policy advice defensible? If so,
on what grounds? If not, then is an alternative approach to policy
analysis and an alternative role for policy modelling indicated?
What constitutes a successful forecast of policy impact? I suggest the
minimal criteria to be a correct forecast of the direction of change in
the magnitude of specified social indicators together with a forecast of
the time lags between policy action and social response. These seem
to me to be such weak criteria that nobody could claim that social
policy modelling has been useful and relevant if they could not be
satisfied.
There are many cases of correct captures of policy indicators calculated
from past data. What we cannot identify are cases where a policy
forecast has been published and then the policy implemented and found to
have the forecast impact on social (including economic) indicators in a
forecast time frame.
I hope you find the question interesting.
Scott
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