The key finding is that “Among violent crimes, the results are negative and statistically significant for murder, rape, and robbery, while the estimate is not significant for assault.” Mello’s findings for murder are limited by the variability in the murder rate, his findings imply that “one life can be saved by hiring about 9.5 new police officers.” Mello goes on to discuss his findings in terms of cost-benefit, finding that each officer contributes $352,000 in social benefit (based on crime reduction) – well above the point at which the additional officer would be considered cost-effective.