ulf christian ewert, mathias roehl and adelinde uhrmacher max planck institute for demographic...
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Ulf Christian Ewert, Mathias Roehl and Adelinde Uhrmacher
Max Planck Institute for Demographic ResearchDoberaner Str. 114D-18057 RostockGermany
Demographic and economic consequences of mortality crises in pre-modern Europe
Does agent-based simulation help to gain new insights into the course of recovery-from-desaster processes?
University of Rostock, Department of Computer Science, Research Group Modelling and SimulationAlbert-Einstein-Straße 21D-18059 RostockGermany
Historical representation of the topic
„Die erschreckliche Wasser-Fluth.” [The horrible storm tide], taken from Happel, „Die größten Denkwürdigkeiten der Welt”, 1683.
Definition Mortality crisis is a decline of populationthat is mortality induced, excessive, rapid, has presumably negative demographic and economic consequences
Modern scientific representation
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TIME (Months)
BIRTHS
DEATHS
BIRTHS (slow recovery)
BIRTHS (stagnation)
Causes of mortality
crises � What are causes of mortality crises?
epidemics, famines, natural desasters, wars
mortality crisis is a structural element of the history of pre-modern Europe!
� Selected example: The Low Countries during late Middle Ages
bubonic plagues (1348, 1400) famines (1315/17; 1407/08; 1437/40) heavy storm tides (1362; 1436) casualities of war (“the Hundred Year’s War”) local desasters (fire in Lille, 1400)
Consequences of mortality crises
� What sort of consequences do we expect?
demographic consequences: sharp fertility decline (increase in fertility) distortion of age and sex ratios
economic consequences: paralysis of local markets sharp increase in food prices increase of nominal wages (per capita income)
cultural consequences: superstitions anticipation of apocalypse
Causal model
� Causal interactions
DESASTER DEMOGRAPHY
ECONOMY
first-order-effects
second-order-effects
second-order-effects
first-order-effects
crisis management
precautionary measures
precautionary measures
crisismanagement
having grain in stock
closing the town;
construction of dikes;
defending the town
attracting in-migration
abolishing marriage regulations
intervening in market processes
starting job-creation programmes
Focus of the analysis
� What is the focus when studying mortality crises?
analysis of the course of the recovery process
assessment of effects of distorted age and sex ratios
judgement of the role of crisis management in overcoming negative consequences of the crisis
� Why can the study of mortality crises be useful for today’s Demography?
comparison to consequences of current desasters in developing countries
Appropriateness of agent-based modelling
� Why agent-based modelling is appropriate to study such crises?
trade-off between historical accuracy and structural simplicity
agent-based modelling enables to distinguish several sorts of reaction patterns to the crisis!
� Example: Medieval and Early Modern Towns
craftsmen: nobody wants to buy their products, marriage plans will be delayed
labourers: real wages are raising, marriage plans can be executed
Actors, Systems, Interactions
� Actors
merchants craftsmen labourers local authority
� Systems grain market consumer good market labour market marriage market public opinion environment of town
represents demographic and economic developments outside of the town
represents the supply of goods to the town
import and sell grain seek to maximize their profit have to find marriage partners
produce and sell goods seek to maximize their profit have to find marriage partners supply labour to craftsmen seek to maxime their savings have to find marriage partners seeks to keep order intervenes in market processes changes market regulations changes marriage norms implements measures to attract in-migration
represents the supply of food to the town
represents the working relations in the town stratified segmentation of actors
strongly regulated by norms emerges from actors’ satisfaction represents degree of order
� Modelling Actors, Systems & Interactions
Modelling
approach framework for modelling & simulation separation between institutions and individuals acting by communication
� Modelling the population – classification utility-based decision making (quantitative) planning (qualitative, symbolic)
Model
� A decision situation current situation: all actor groups are unsatisfied supply of grain and labour is too low in the town supply of consumer goods is sufficient Local Authority has little money and much grain available
selected goals: all actor groups should be satisfied sufficient supply of labour, grain and goods Local Authority has still some money available
Sample scenario
� Where do we stand?
State-of-the-art
agents (local authority): specification of beliefs, desires, plan operators integration of general planning system (GraphPlan) planning experiments: exploring the interplay between beliefs, desires, plan operators
actors (merchants, craftsmen, labourers): modelling of utility-based decision rules but not yet tested
institutions (markets, public opinion, environment of the town): modelling of general structure but not yet tested
� Implementation in JAMES
sound system theoretic foundation (DEVS)
a J ava-based A gent M odelling E nvironment for S imulation
clear separation between model & simulation modular hierarchical composition parallel, distributed execution variable structure models
Simulation
� Does agent-based simulation help to gain new insights into the course of recovery-from-desaster processes?
Prospects of the
model � What are future prospects of the model?
reproduction of recovery-from-desaster processes on the basis of micro-macro-level interactions measurement of the relative impact of demographic and economic distortions
comparison of recovery processes due to different causes and characteristics of the crisis comparison of scenarios with various degrees of intervention by the local authority
simulation of sequential desasters with learning agents (local authority)