Philadelphia’s proposed city budget adds an unprecedented $68.3 million to the existing $87 million anti-violence funding. This is a historic opportunity to address violence in the city and increase our understanding of what programs work to reduce violence in our communities. But the evidence from previous spending cycles suggests it will be wasted.

This is not to claim funds for mental health coresponse programs, violence intervention, community organizations, summer programs, curfew centers, and jobs programs are ineffective. On the contrary, they may be just what we need. But without incorporating a thorough evaluation, we may never learn which programs contribute to the city’s violence prevention, and which do not.

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Why is evaluation so important? Our budget woes are projected to continue for years, and we are unlikely to have $150 million for anti-violence funding in coming years. In the near future, politicians will have to make difficult decisions around which programs to expand, which to keep, and which to let fall by the wayside. The current rhetoric from City Hall confidently asserts they will all work, and assuming all these well-intentioned efforts will reduce violence is natural. But it is not necessarily warranted.

Many years ago, my former Temple colleague, Joan McCord, published a landmark study. She evaluated an extensive program in Cambridge and Somerville, Mass., that provided at-risk youth with years of family counseling, access to social workers, academic assistance, and recreational activities. The program epitomized the immersive assistance for troubled youth advocated by social work experts and was fully expected to be a roaring success. Unfortunately, Joan found that — compared with equivalent children — kids chosen for the program were later shown to have engaged in more crime, were more likely to be charged and appear in court, and were more likely as adults to have been convicted of serious street crime.

We know from research conducted right here in Philadelphia that police foot patrols, focused deterrence, and addressing vacant land have all demonstrated a capacity to positively influence violence. But violence preventers, community empowerment, and video cameras at rec centers are all untested interventions. Next year, we may need to make some difficult decisions about whether to keep certain initiatives. Given the paucity of existing knowledge, incorporating a robust evaluation into the coming budget expenditure will be essential to inform those hard choices. But with rare exceptions, the city has regularly spent tens of millions on untested programs with no evidence they work.

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We have an unprecedented opportunity to gain vital insights for our future community safety investment. The city has no shortage of academic departments at various universities versed in effective evaluation. It may be better to give them a couple of percents and learn whether the remaining 98% works. Otherwise, we throw 100% of the money at well-meaning interventions yet remain ignorant on which programs actually deliver and on which we should double down. Lurching from year to year, spending tens of millions of taxpayer dollars with no evidence of effective service delivery is reckless, and potentially harmful to our high-crime neighborhoods that need the most help.

Joan McCord’s groundbreaking research on the Cambridge Somerville Youth Study is a cautionary lesson that well-meaning initiatives can backfire in unexpected ways. We can avoid this pitfall if we make smart funding choices. Outcome-focused assessment will pay dividends for city community safety investments for years to come.

Jerry Ratcliffe is a professor in the department of criminal justice at Temple University and the host of the “Reducing Crime” podcast.