Journal on Policy and Complex Systems
demonstrates the usefulness of computational modeling and simulation in this domain by examining how the two policy approaches impact child sex trafficking . The standards in the Overview , Design Concepts , and Details protocol ( ODD ) guide documentation of the model and simulation ( Grimm et al ., 2010 ).
The Model : Overview , Design Concepts , and Details ( ODD )
Overview Purpose . This ABM examines the ways in which two law-enforcement strategies influence child sex trafficking in King County , Washington . These interventions are a ) targeting supply by arresting and prosecuting child victims of sex trafficking and b ) targeting demand by arresting and prosecuting buyers who purchase sex from children . The model simulates these two law-enforcement strategies in an artificial society and generates outputs in the form of the number of children trapped in commercial sex trafficking and the number of commercial sex transactions with children . Output data can be interpreted as a measure of policy effectiveness . An associated goal is to demonstrate the effectiveness of computational modeling and simulation for analyzing policy proposals in this domain .
Entities , state variables , and scales . CSEC entities are prostituted persons ( children ), buyers ( johns ), suppliers or pimps ( traffickers ), and the law-enforcement officials who combat trafficking of children ( police ).
Children are characterized by two state variables : act and desired sale . The variable act represents the number of commercial sex transactions . At initialization , act has a value of zero , which means zero commercial sex transactions , and then it increments each time an individual interacts with a buyer . The value of desired sale is based on the quota set by pimps in Seattle . With each commercial sex transaction , the value of desired sale updates . Each child ’ s objective is to fulfill the desired sale during the period of a simulation run .
Each buyer is assigned two state variables : purchase and purchase threshold . The purchase variable increments each time a buyer makes a purchase . The purchase threshold variable is the number of times a buyer wants to purchase sex in a year and is initialized using Monto and Milrod ’ s ( 2013 , p . 802 ) survey data of buyers . This dataset presents the number of times buyers had sex with a prostitute during the previous year .
In the Buyer Beware program , the police in King County committed to running monthly or bimonthly sting operations ( Demand Abolition ’ s CEASE Network Seattle ). The number of police departments plays no role in model dynamics . Depending on the policy in place , in sting operations police randomly arrest buyers or children . According to Farley et al . ( 2011 ), 100 % of interviewed sex buyers reported that they would be deterred if they were sentenced to a one-month jail term . Therefore , the model assumes that once purchasers are arrested , they are de-
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