Pattern oriented modeling

Pattern Oriented Modeling (POM) is an approach to bottom-up complex systems analysis which was developed in ecology and for agent-based complex systems. A goal of POM is to make ecological modeling more rigorous and comprehensive [Grimm, V. and S.F. Railsback. Individual-based modeling and Ecology. Princeton University Press., Princeton, NJ, 2005.] . A traditional ecosystem model attempts to approximate the real system as closely as possible. POM proponents posit that an ecosystem is so information-rich that an ecosystem model will inevitably either leave out relevant information or become over-parameterized and lose predictive power [Grimm, V.; Revilla, E.; Berger, U.; Jeltsch, F.; Mooij, W.M.; Railsback, S.F.; Thulke, H.H.; Weiner, J. Wiegand, T. and D.L. DeAngelis. 2005. Pattern-Oriented Modeling of Agent-Based Complex Systems: Lessons from Ecology. Science 310, 987-991] . Through a focus on only the relevant patterns in the real system, POM offers a meaningful alternative to the traditional approach.

A return to the scientific method, POM requires the researcher to begin with a pattern found in the real system, posit hypotheses to explain the pattern, and then develop predictions which can be tested. A model used to determine the original pattern may not be used to test the researcher’s predictions. Through this focus on the pattern, the model can be constructed to include only information relevant to the question at hand [Grimm, V.; Franka, K.; Jeltsch, F.; Brandla, R.; Uchmariskib, J. and C. Wissela. 1996. Pattern-oriented modeling in population ecology. The Science of the Total Environment 183: 151-166.] .

POM is also characterized by an effort to identify the appropriate temporal and spatial scale at which to study a pattern, and to avoid the assumption that a single process might explain a pattern at multiple temporal or spatial scales. It does, however, offer the opportunity to look explicitly at how processes at multiple scales might be driving a particular pattern [Grimm, V.; Revilla, E.; Berger, U.; Jeltsch, F.; Mooij, W.M.; Railsback, S.F.; Thulke, H.H.; Weiner, J. Wiegand, T. and D.L. DeAngelis. 2005. Pattern-Oriented Modeling of Agent-Based Complex Systems: Lessons from Ecology. Science 310, 987-991] .

A look at the trade-offs between model complexity and payoff can be considered in the framework of the Medawar zone, where the model is considered too simple if it addresses a single problem (eg, the explanation behind a single pattern), whereas it will be considered too complex if it incorporates all the available biological data. The Medawar zone, where the payoff in what is learned is greatest, is at an intermediate level of model complexity.

Pattern oriented modeling has been used to test a priori hypotheses on how herdsman decide which farmers to contract with when grazing their cattle. Herdsman behavior followed the pattern predicted by a 'friend' rather than 'cost' priority hypothesis ^[2] .

References

1. [http://books.google.com/books?hl=en&lr=&id=12MvUbMeog8C&oi=fnd&pg=PR11&dq=grimm+POM&ots=_tn6cXpw7L&sig=7jDBUumGS7Ze6WCpmKXUrhwyCJk Grimm, V. and S.F. Railsback. Individual-based modeling and Ecology. Princeton University Press., Princeton, NJ, 2005.]

2. [http://www.sciencemag.org/cgi/content/abstract/310/5750/987 Grimm, V.; Revilla, E.; Berger, U.; Jeltsch, F.; Mooij, W.M.; Railsback, S.F.; Thulke, H.H.; Weiner, J. Wiegand, T. and D.L. DeAngelis. 2005. Pattern-Oriented Modeling of Agent-Based Complex Systems: Lessons from Ecology. Science 310, 987-991. ]

3. [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V78-3VW2B4P-1H&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ce3afe3fec1be139c4c66348e7b0961d Grimm, V.; Franka, K.; Jeltsch, F.; Brandla, R.; Uchmariskib, J. and C. Wissela. 1996. Pattern-oriented modeling in population ecology. The Science of the Total Environment 183: 151-166.]

4. [http://pt.wkhealth.com/pt/re/oiko/abstract.00010351-200302000-00001.htm;jsessionid=LXVPsv5y0XS2PwSjsyhQQnsrp6fnpdhjCvhRL2K5Sdp1Qwbkftcx!1167962659!181195628!8091!-1 Wiegand, T. Jeltsch, F. hanski, I. and V. Grimm. 2003. Using pattern-oriented modeling for revealing hidden information: a key for reconciling ecological theory and application. OIKOS 100: 209-222.]