Targeting Escalation in Intimate Partner Violence: Evidence from 52,000 Offenders

06 Apr 2018

Research Question Does the severity or frequency of intimate partner violence or abuse reported to police increase over time, once a unique perpetrator-victim couple has come into contact with police in Thames Valley UK? Data A total of 140,998 recent (non-historical) incidents of intimate partner violence or abuse reported to Thames Valley Police in 2010-2015 were identified, with 52,296 unique perpetrators for whom a standard 731-day observation period was possible after each perpetrator’s first incident was reported in the intake period from 1st January 2010 through 31st December. Duplicate entries were eliminated and standard eligibility criteria were assured by data-cleaning from the NICHE records management system of Thames Valley Police. Methods All non-crime incidents or reports of crime against intimate partners were coded by the Cambridge Crime Harm Index (CHI) with the sum of total days of recommended imprisonment for each offence (as the guideline starting point for sentencing) summed across all offences for each offender (Sherman, et al 2016), with CHI scores for each successive incident plotted in sequence. Prevalence and frequency of repeat police contacts were also computed for each perpetrator, as well as the conditional probability of each new offence given the number of prior offences. Findings Most perpetrators identified in the 52,296 initial reports (77.6%) had no report of crime after the initial report. A further 21.2% had crime harm totals of less than 10 days of recommended prison time, with only 893 (1.7%) of the total universe of four years’ worth of perpetrators who had a reported crime harm total over offences with a recommendation of over 10 days sentencing in the 731-day observation period. A slightly larger “power few” of 3% of perpetrators accounted for 90% of total intimate partner abuse crime harm inflicted by all perpetrators, while 97% of perpetrators produced only 10% of total crime harm. Overall, among the few who had numerous repeat incidents, there was increasing frequency but no evidence of increasing seriousness of harm caused to victims. The 100 most harmful offenders in 2010 maintained a high (but greatly decreased) level of harm in 2011, but on average were very-low harm offenders in 2012-15. Conclusions This analysis suggests that the intimate partner abuser population is highly segmented in Thames Valley, with a small power few inflicting most of the harm. While the most serious offenders may remain difficult to identify prospectively, any valid prediction model could help to prevent a substantial amount of crime harm against intimate partners. Investing in such prediction methods may do more to help victims than an undifferentiated strategy putting most resources into low-risk cases. Keywords Intimate partner violence – policing –Crime Harm Index—Forecasting High Harm