Pattern-oriented modeling (POM) is an approach to bottom-up
complex systems
A complex system is a system composed of many components which may interact with each other. Examples of complex systems are Earth's global climate, organisms, the human brain, infrastructure such as power grid, transportation or communication s ...
analysis that was developed to
model complex ecological and
agent-based
An agent-based model (ABM) is a computational model for simulating the actions and interactions of autonomous agents (both individual or collective entities such as organizations or groups) in order to understand the behavior of a system and wha ...
systems. A goal of POM is to make ecological modeling more rigorous and comprehensive.
[Grimm, V.; Railsback S.F. (2005), ''Individual-based Modeling and Ecology'', Princeton University Press.]
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.; DeAngelis D.L. (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.
An attempt to mimic 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 that 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.; Frank, K.; Jeltsch, F.; Brandl, R.; Uchmariski, J.; Wissel C. (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.
A look at the trade-offs between model complexity and payoff can be considered in the framework of the
Medawar zone
The Medawar Zone is the area of problems which are most likely to produce fruitful results. Problems that are too simple are unlikely to produce novel or significant results. Problems that are too ambitious may not succeed at all or may be rejecte ...
. The model is considered too simple if it addresses a single problem (e.g., 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.
Usage
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.
References
{{refbegin
Complex systems theory