What factors can really help drive down crime? The National Academies of Sciences, Engineering and Medicine said in a report released Thursday that certain “proactive” policies aimed at preventing crime before it happens—including stop and frisk—show mixed results. Yet it is not enough to simply identify what policies appear to reduce crime, a panel convened by the National Academies cautions in the report. Authorities must also consider the real-world risks of applying these approaches in ways that are biased or illegal, they wrote.

Historically, policing has focused largely on responding to calls and investigating crimes. But in the past few decades there has been a shift toward preventing crime by routinely sending officers into communities and identifying potential problem areas. Not all police departments are using these strategies, notes David Weisburd, chair of the expert panel and director of the center for evidence-based crime policy at George Mason University. But it is becoming relatively common and is a big departure from the standard model, in which police mostly respond to crimes that already occurred, Weisburd told Scientific American .

“For police chiefs who want to do something, increases in violent crime are often very localized and occur among specific people and on specific streets—and the evidence from the report is that when you focus on those, you can produce reductions in crime,” Weisburd says. “Hot-spotting,” for example—a practice in which police are disproportionately stationed in areas with higher crime rates—seems to help, and does not just displace crime into immediately surrounding areas, the committee says. And stop and frisk can be effective when it is highly focused on areas with high concentrations of crime or robberies, Weisburd adds. His committee also found that third-party policing—in which businesses or building owners partner with police or are pressured to work with them—can help. When police officers identify specific problems, try to understand them and make a tailored plan to solve them, it can reduce crime, too. Finally, focusing police resources on high-rate offenders (to either get them off the street or reduce crime) has good evidence behind it.