An impact evaluation found that UPPs had mixed results. The evaluation found no significant impact of UPPs on reducing homicides among community residents (small impact, close to zero). However, the same study noted that the program had a strong impact on reducing deaths due to police intervention in those areas. The results of the study point to a reduction of 29 police-involved deaths (per 100,000 inhabitants per year) in the intervention areas compared to the comparison group areas. The authors also estimate that, without UPPs, police-caused death rates per 100,000 inhabitants would be 60% higher than the observed records. Police-caused death rates for black males fell from more than 25 to less than 7 per 100,000 inhabitants from 2007 to 2013 [1].
Five years later, this study was updated (with data collected between 2005 and 2015, and with 164 favelas contemplated in the treatment group) and republished with its new findings. According to the authors, in about 60% of the territories where the intervention was carried out, the UPPs managed to reduce common crimes, such as homicides, extortions, and robberies, and to achieve community acceptance. However, the UPPs deteriorated public security in 40% of the territories where they were implemented, where they also failed to gain legitimacy. Furthermore, the size of the effect of UPPs on police-caused deaths was estimated at -1.13, which means a reduction of 1.3 police homicides per 100,000 inhabitants per month. These estimates suggest an annual reduction of about 133 killings, which would represent a roughly 40% reduction in the number of police-caused homicides thanks to the UPPs [2].