Journal on Policy & Complex Systems Volume 5, Number 2, Fall 2019 | Page 112

Analyzing the Effectiveness of Anti-Child-Sex-Trafficking Policies Targeting Demand versus Supply Using Agent-Based Modeling
Figure 1 . Pre-change policy situation ( 2009 ).
intervention focused on targeting supply in terms of reducing the number of trafficked children forced into the commercial sex industry . This finding aligns with existing literature , which shows very little empirical evidence for the effectiveness of targeting supply in commercial sexual exploitation ( Shively et al ., 2012 ).
Figure 1 is the simulation grid for the pre-change policy situation ( 2009 ).
The simulation grid for the postchange policy situation ( 2015 ) has a few differences , as the following annotated screen capture shows ( Figure 2 ).
Figure 3 depicts the percentage difference between purchases in 2009 and purchases in 2015 over the one-year period of the simulation , with 52 oneweek time-steps . A positive percentage number indicates that the 2009 number is higher by that percentage than the
2015 number . At the beginning of the year , there is not much difference , but the difference grows , producing an endof-year situation in which there are 1.5 % fewer purchases in 2015 than in 2009 , with a 3.5 % decrease in the number of buyers in 2015 . Since the simulation runs reflected the policy change from supply-side arrests to demand-side arrests , and since these models are causal and not merely correlational ( as statistical models are ), we know that the change occurs because of the policy shift .
We can also use the number of prostituted minors over the course of one year to evaluate the policy change ( Figure 4 ). The blue line tracks 2009 conditions ( with a supply-side focused law-enforcement policy ). The orange line tracks the relatively stable number of prostituted minors in the model over time under 2015 conditions ( with a demand-side focused policy ).
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