Relative Impact of Underreporting and Desistance on the Dark Figure of Sexual Recidivism

Sexual recidivism rates based on arrests or convictions underestimate actual reoffending due to underreporting. A previous Monte Carlo simulation estimated actual recidivism rates under various reporting and conviction assumptions but did not account for desistance-the decreasing likelihood of reoffending over time. This study addresses that gap by incorporating a 12.3% annual desistance rate (from a well-known empirical study) and exploring its impact alongside varying charge rates (100%-5%). The results showed that reductions in charge rates lead to disproportionately large increases in recidivism. For instance, lowering the charge rate from 50% to 25% results in a much larger increase in actual recidivism than reducing it from 100% to 75%, despite both being 25% reductions. This indicates that as charge rates decrease, actual recidivism grows more sharply. A sensitivity analysis also examined desistance rates of 0%, 5%, 12.3%, and 20%. Higher desistance rates cause reoffending to occur earlier but have little impact on long-term totals. Over 25 years, reoffending rates remain similar across desistance rates, suggesting desistance affects the timing, but not the overall amount of reoffending.