Go through the NPR study carefully and then index it to other studies. I think the NPR study is pretty accurate, but the article is misleading in a few areas.
Only a small percentage of homicides are impacted by police staffing levels. Not sure why NPR even used that as a measure of effectiveness. That is pretty misleading, but even there NPR acknowledged that the small percentage of homicides subject to being impacted by police presence nationally was in fact impacted positively.
Property crimes are more impacted by additional police officers, studies show for every incremental dollar spent on law enforcement salaries, property crime drops $3. Of course, the savings are higher in high crime areas and lower in low crime areas. As an aside, many of these property crimes are classified as "victimless" crimes because no one got hurt.
The NPR study confirms that more police on the street does reduce the incidence of crime with or without more arrests.
More evidence that police staffing levels impact the risk reward outcomes tied to crime. The best outcome of more police is that the crime never takes place. People choosing not to commit crimes because they fear getting arrested is the goal, the arrests are there to create the deterrent.
The presence of police is like casting a net... both big fish (violent crimes) and little fish (nonviolent crimes) get caught in the net. So, a disproportionate number of low-level "victimless" crime arrests are expected to happen in areas where more police are assigned. If you live in a POC dominated neighborhood, like my daughter, you are okay with police arresting people who commit crimes... victim or not.
So, that is not a "bad" thing, nor is it a "policing" issue. Their job is to enforce the law and let the justice system figure out how to deal with them fairly.
Sounds like you have issues with how the justice system deals with nonviolent crime. That is a different issue. The issue of how the justice system should address low level crimes is a big one here in California. Since we redefined low level crimes, we have people who are making a career out of low-level crimes. But low-level crimes can quickly escalate when the victim fights back.
Before we redefined low level crimes, I rarely saw a car window smashed by a car theft. Now I see several a month on my walks and I live in a very good neighborhood. I am not opposed to criminal reform, but what we called reform is not working.
I am surprised the NPR article did not point out African Americans are the strongest advocates of maintaining or increasing police presence in their communities. Isn't that relevant to the subject of the NPR article since at some level it suggests institutional racism.
African Americans are not playing games with numbers, they understand the trade-offs and most choose more police even with the negatives that go along with that choice.
Another example, of people understanding the realities of their neighborhoods. Asians are highest among demographic groups wanting less police presence. The survey correlates almost perfect with crime statistics by racial demographic.
https://news.gallup.com/poll/316571/black-americans-police-retain-local-presence.aspx
The NPR study defined its own reason for why police officers exist (to reduce homicide rates) and then argued that more police leave some cities worse off. But again, according to my brother and police officers I have talked to... policing is largely about avoiding property crimes and encouraging compliance with the laws.
Nationally, homicides related to those activities do go down, but most homicides are related to drug and gang activities and take place in poor communities with relatively low level of policing especially at night. Those crimes are not what police in general focus on but are addressed by detectives that track down the killers and try to send them to prison for a long time. Getting "killers" off the street is a totally different issue than reducing crime and relies on different resources.
If reducing inner city drug and gang related homicide is the goal, then you need to target those activities. Some major cities do have police units targeting those activities with success, it was misleading for the NPR article to suggest that homicide rates were relevant when it comes to police staffing.
The NPR article was pushing a bit of narrative. If it really wanted to study the issue. It might have gone to some of those southern and Midwestern cities where incremental police officers were added to see why and how they were hired and did they produce the intended effect. If so, then those cities got what they paid for.
