Analyzing the Effectiveness of Anti-Child-Sex-Trafficking Policies Targeting Demand versus Supply Using Agent-Based Modeling
terred from going back to purchasing commercial sex for the duration of the simulation period of one year . Similarly , children who get arrested will not be prostituted after they get arrested . In other words , we assume that the recidivism rate of arrested buyers and arrested children is zero within the simulation period , which is one year .
On average , every pimp in Seattle controls three girls ( Dank et al ., 2014 ). However , the number of traffickers plays no role in model dynamics , so all girls are treated as being controlled by a single trafficker . At each time step , if supply is lower than demand , that trafficker recruits one person to meet the demand .
Process overview and scheduling . According to his purchase threshold , each buyer randomly interacts with one prostituted child , who has a desired sale greater than 0 . As a result of this interaction , the state variables , purchase threshold , desired sale , act , and purchase are updated . The values of purchase threshold and desired sale decrease . The values of act , which counts commercial sex transactions , and purchase , which captures the number of purchases , increment . Every time-step when supply is lower than demand , the trafficker will recruit a prostituted person to increase the supply . Supply is the sum of desired sale of prostituted children . Demand is the sum of purchase threshold of buyers .
Design Concepts
In the simulation , each time step represents one week and the simulation stops when one year is completed , at step 52 . The entities are randomly located on a grid . Different colors of buyers represent their purchase threshold . Yellow represents buyers with a purchase threshold of zero . Brown represents buyers with a purchase threshold of once a year . Blue represents buyers with a purchase threshold of less than one time a month . Grey represents buyers with a purchase threshold of twice a week . White represents buyers with a purchase threshold of three times a week . The buyers ’ color changes to green after getting arrested . Prostituted children are displayed in red . Children ’ s color changes to orange after getting arrested .
Basic principles . This model applies the economic principle of demand and supply to child sex trafficking . The demand-supply framework has not been previously applied to an agent-based model of child sex trafficking .
Emergence . There is variability in the number of purchases each buyer can make . The number of purchases and the demand for commercial sex emerge from interaction between buyers and sellers .
Sensing . Buyers know whether the variable desired sale is above zero . They purchase sex from a prostituted child having a desired sale of greater than zero .
Interaction . Buyers and prostituted children interact if the buyers did not reach their purchase threshold and if the prostituted children have a desired sale of greater than zero .
Stochasticity . The interaction between buyers and prostituted persons is a stochastic process because interaction partners are chosen randomly .
Observation . Two plots are used for
105