Journal on Policy and Complex Systems
between 1960 and 2010 . Fertility is measured as a rate of population change in the absence of migration . Income is measured as GDP per capita , and then normalized using logarithmic function . Political instability captures the proportion of the physical capital stock destroyed in antigovernment uprising . These three variables are measured in the same way as the original model ( Feng et al ., 2000 ). Instead of the literacy rate , I use the gross secondary school enrollment ratio for all programs per thousand people to measure human capital , because the original measure lacks desired variation and is inappropriate for estimation . We also update the measure for political capacity . Instead of using relative political extraction alone , we incorporate both relative political extraction and relative political reach as indicators of political capacity , to provide more granular measures and policy levers of the government ’ s input policy . Relative political extraction incorporates the actual total tax revenue of a country and compares it with predicted total tax revenue , while relative political reach gauges the capacity of governments to influence and mobilize populations under their control ( Kugler & Tammen , 2012 ). The three-stage least-squares model is specified in above systems of equations , with one at the aggregated individual level focusing on human capital , fertility , and income , as those variables come from individual decisions and interactions , while the other at the society level focusing on instability and political capacity , as those two variables are better captured at the macro level instead of the micro level , though some explanatory variables are measured from the aggregation of individual variables . Besides supporting original POFED theory , this step is necessary because it provides empirically validated coefficients in the multilevel agent-based model .
5 . Multilevel Simulation Model
We propose an agent-based model in a complex adaptive system framework that captures both macrolevel changes and microlevel behavior by incorporating a system dynamics component and a game theory component . Following the work by Abdollahian et al . ( 2013 , 2014 , 2015 ), this model has both the interactive effects and feedbacks between individual human agency as well as the macro constraints and opportunities that change over time for any given society . Individual decisions are affected by other individuals , social context , and system states . These elements have first- and second-order effects , given any particular system state or individual attributes .
Such an approach attempts to increase both theoretical and empirical verisimilitude for some key elements of complexity processes , emergence , connectivity , interdependence , and feedback found throughout several disciplines across all scales of development . There are three modules in the agent-based model : micro-agent process , macro-society process , and heterogeneous evolutionary game process . The accompanying pseudocode is shown below :
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