In criminal justice, clearance rate is calculated by dividing the number of crimes that are "cleared" (a charge being laid) by the total number of crimes recorded. Clearance rates are used by various groups as a measure of crimes solved by the police.
Clearance rates can be problematic for measuring the performance of police services and for comparing various police services. This is because a police force may employ a different way of measuring clearance rates. For example, each police force may have a different method of recording when a "crime" has occurred and different criteria for determining when a crime has been "cleared." One police force may appear to have a much better clearance rate because of its calculation methodology.
In System Conflict Theory, it is argued that clearance rates cause the police to focus on appearing to solve crimes (generating high clearance rate scores) rather than actually solving crimes. Further focus on clearance rates may result in effort being expended to attribute crimes (correctly or incorrectly) to a criminal, which may not result in retribution, compensation, rehabilitation or deterrence.
How Many Crimes Do Your Police 'Clear'? Now You Can Find Out.
Violent crime in America has been falling for two decades. That's the good news. The bad news is, when crimes occur, they mostly go unpunished.
For most major crimes, police don't even make an arrest or identify a suspect. That's what police call "clearing" a crime; the "clearance rate" is the percentage of offenses cleared.
In 2013, the national clearance rate for homicide was 64 percent, and it's far lower for other violent offenses and property crimes.
University of Maryland criminologist Charles Wellford says police have shifted priorities over the decades.
"In the '60s and '70s, no one thought that the police should be held responsible for how much crime there was," Wellford says. Back then, he adds, police focused on calls for service and solving crimes.
In more recent years, he says, police have been pushed to focus more on prevention, which has taken precedence over solving crimes — especially non-violent offenses.
In short, the falling crime rate we've enjoyed may come at a cost: police indifference when you report your stereo was stolen.
The FBI collects clearance statistics for its annual "Uniform Crime Report," but it doesn't break those numbers down by jurisdiction. That makes it hard for people to compare local police departments' clearance rates, or track them over time.
The quality of American crime statistics is notoriously uneven, and these are no exception. Sometimes cities fail to report, or their data are rejected because of errors. For instance, this database shows the New York Police Department clearing zero homicides in 2011 and 2012 — clearly not the case.
These data follow the standards of the FBI's Uniform Crime Report. One of the idiosyncrasies of UCR Summary data is that clearances are credited to the year in which the crime was cleared, not the year in which it was committed. As a result, it's sometimes possible for a city to clear more murders than were committed in a year, for a clearance rate above 100 percent.
Some cities will claim different clearance rates, based on another federal statistical standard known as the NIBRS. We decided to stick with the more widely-used UCR Summary standard, to allow people to compare like with like. (Here is an explanation of the differences between UCR and NIBRS.)
Clearance statistics for sexual assault are left out because experts in the field have advised us that reporting inconsistencies make those data too unreliable.
FBI for the 2014 clearance rates will be added when those become available.
Open Cases: Why One-Third Of Murders In America Go Unresolved
If you're murdered in America, there's a 1 in 3 chance that the police won't identify your killer.
To use the FBI's terminology, the national "clearance rate" for homicide today is 64.1 percent. Fifty years ago, it was more than 90 percent.
And that's worse than it sounds, because "clearance" doesn't equal conviction: It's just the term that police use to describe cases that end with an arrest, or in which a culprit is otherwise identified without the possibility of arrest — if the suspect has died, for example.
Criminologists estimate that at least 200,000 murders have gone unsolved since the 1960s, leaving family and friends to wait and wonder.
Homicide detectives say the public doesn't realize that clearing murders has become harder in recent decades. Vernon Geberth, a retired, self-described NYPD "murder cop" who wrote the definitive manual on solving homicides, says standards for charging someone are higher now — too high, in his opinion. He thinks prosecutors nowadays demand that police deliver "open-and-shut cases" that will lead to quick plea bargains.
He says new tools such as DNA analysis have helped, but that's been offset by worsening relationships between police and the public.
"If there is a distrust of the police themselves and the system, all of these scientific advances are not going to help us," he says.
Since at least the 1980s, police have complained about a growing "no snitch" culture, especially in minority communities. They say the reluctance of potential witnesses makes it hard to identify suspects.
But some experts say that explanation may be too pat. University of Maryland criminologist Charles Wellford points out that police are still very effective at clearing certain kinds of murders.
"Take, for example, homicides of police officers in the course of their duty," he says. On paper, they're the kind of homicide that's hardest to solve — "they're frequently done in communities that generally have low clearance rates. ... They're stranger-to-stranger homicides; they [have] high potential of retaliation [for] witnesses." And yet, Wellford says, they're almost always cleared.
What that tells Wellford is that clearance rates are a matter of priorities.
Wellford says Americans should also understand that while the national rate is in the 60s, the local rates vary widely. But because the FBI doesn't publish local agencies' numbers, these differences are often invisible to the public.
NPR had to make a special request for those local clearance rates. You can find them, by city, using our look-up tool, and can learn more about clearance rates — and why local data can be difficult to obtain.
Look Up Crime Clearance Rates In Your Community:
- The encyclopedia of police science, Volume 1 By Jack R. Greene, http://books.google.com/books?id=HIE_zF1Rv7MC&lpg=PA907&=fVuvhI2iZL&dq=definition%20%22clearance%20rate%22%20police&pg=PA907#v=onepage&q=definition%20%22clearance%20rate%22%20police&f=false
- Martin Kaste, NPR, March 30, 2015, Morning Edition
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