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--- geopro:pedro:models [2008/06/19 18:35] – pedro
+++ geopro:pedro:models [2008/06/20 19:16] (atual) – pedro
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 ====== Agent-Based Models ======
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 \\
+====Policy analysis from first principles====
+|S Moss, 2002| PNAS 99(3)7267–7274| [[http://www.leg.ufpr.br/~pedro/papers/pnas/policy-analysis-moss.pdf|pdf]]|
+{{  http://www.leg.ufpr.br/~pedro/figures/moss-sales-grid-size.jpg}}
+\\
+**Abstract:** The argument of this paper is predicated on the view that social
+science should start with observation and the specification of a
+problem to be solved. On that basis, the appropriate properties and
+conditions of application of relevant tools of analysis should be
+defined. Evidence is adduced from data for sales volumes and
+values of a disparate range of goods to show that frequency
+distributions are commonly fat-tailed. This result implies that **any
+stable population distribution will generally have infinite variance
+and perhaps undefined mean**. Models with agents that reason
+about their behavior and are influenced by, but do not imitate,
+other agents known to them will typically generate fat-tailed time
+series data. A simulation model of intermediated exchange is
+reported that is populated by such agents and yields the same type
+of fat-tailed time series and cross-sectional data that is found in
+data for fast moving consumer goods and for retail outlets. This
+result supports the proposition that **adaptive agent models of
+markets with agents that reason and are socially embedded have
+the same statistical signatures as real markets**. Whereas this
+statistical signature precludes any conventional hypothesis testing
+or forecasting, these models do offer unique opportunities for
+validation on the basis of domain expertise and qualitative data.
+Perhaps the most striking conclusion is that neither current social
+theory nor any similar construct will ever support an effective
+policy analysis. However, adaptive agent modeling is an effective
+substitute when embedded in a wider policy analysis procedure.
+\\
 ====Constructing and Implementing an Agent-Based Model of Residential Segregation through Vector GIS====