The trick to D.C. police force’s 94% closure rate for 2011 homicides
The article about the D.C. police department’s homicide-closure statistics suggested that the department may have manipulated data to foster a positive impression of the force’s performance.
The article characterized the department’s reporting of homicide-closure rates as a “statistical mishmash that makes things seem much better than they are.” It also suggested that the department’s methodology produced a number that was not “a true closure rate.” As a result, the article, as well as elements of the headline and an accompanying graphic, implied that the department artificially inflated public data on the number of cases that are closed each year.
In fact, as the article reported, the department has followed practices consistent with federal crime-data guidelines and relied upon the same methodology used by other major municipal police agencies. The department hasn’t altered the ways it calculates homicide-closure rates since Cathy L. Lanier became chief in 2007, and it discloses its methodology in its annual report.
The data the department publicly reports include prior-year cases that are opened or closed during the calendar year. In recent years, the closures of cases from earlier years have tended to enhance closure rates. For capturing the department’s performance over time, that may be a statistically valid approach, although it could leave the impression that police are solving current-year cases faster than they actually are. The decision to publicly cite the higher rate casts the department in a more favorable light but does not mean that the underlying data are distorted.
* * *
For the past two months, D.C. Police Chief Cathy L. Lanier has touted the city’s astronomically high homicide closure rate — 94 percent for 2011 — and warned anyone contemplating murder in the District to think twice.
“Your risk of being caught is pretty high if you commit a homicide in D.C.,” Lanier told The Washington Post in December.
The closure rate she presents for the District is 154 percent higher than Boston’s and at least 104 percent higher than Baltimore’s, and it gives residents reason to believe that D.C. police have been remarkably successful at solving homicide cases under her watch.
But an examination of District homicides found that the department’s closure rate is a statistical mishmash that makes things seem much better than they are. The District had 108 homicides last year, police records show. A 94 percent closure rate would mean that detectives solved 102 of them. But only 62 were solved as of year’s end, for a true closure rate of 57 percent, according to records reviewed by The Post.
D.C. police achieved the high closure rate last year by including about 40 cases from other years that were closed in 2011.
The cases date from 1989, records show. The pattern was first reported by a local Web site, homicidewatch.org, in D ecember.
Lanier said the department followed FBI Uniform Crime Reporting guidelines in calculating its homicide clearance rate.
“The UCR guidelines have been used to report on clearance rates as long as anyone here can remember, and is not unique to my tenure as Chief of Police,” Lanier said in a response to written questions. “Most agencies across the country use the same guidelines and rules in reporting homicide clearance rates.”
Uniform Crime Reporting
Lanier referred a reporter to the FBI’s Uniform Crime Reporting Web page. A separate FBI publication on law enforcement records says only that a clearance rate is calculated by dividing the number of offenses cleared by the number of offenses known.
Each year, police departments across the country send their crime statistics to the FBI’s UCR Program, reporting the number of crimes that occurred in a year and the number that were closed — or solved — in that year. But the numbers are not necessarily connected to each other: Crimes cleared in one year might have occurred in another.
When asked by The Post for statistics, some departments — those in Baltimore, Chicago and Prince George’s County — provided two sets of closure data, one with just the cases from a particular year and one with older cases included. Boston counted only closures from a particular year.
Several local law enforcement veterans and some criminologists from around the nation said that including older cases produces a misleading impression.
W. Louis Hennessy, a former D.C. police captain who oversaw the homicide unit from 1993 to 1995, called such statistics “entirely unfair.”
Hennessy said D.C. police in the past calculated the closure rate by using only homicides that happened in a particular calendar year. When the closure rate declined in the 1980s, he said, the department switched to using the UCR totals, making it appear that the department was solving more homicides.
“I felt like anytime you could have more than 100 percent, it’s a little bit misleading and deceiving,” said Hennessy, who is now a Maryland District Court judge. “When I came in, I changed it back. If we look like we’re deceiving or being deceitful, how can we, in good faith, ask them [people] to put their lives on the line?
“We have problems, and the more that the community knows we have problems, the better off we are. You don’t want to mislead people and have them come back and question our motives.”
The Lanier record
Homicides have dropped significantly during Lanier’s tenure, and the true closure rate has also improved, The Post found. But the practice of counting closures of older cases as well as those from the year being reported has helped boost the rate every year since Lanier was confirmed as chief in April 2007.
For 2010, she reported a 79 percent closure rate, but The Post found that the department solved 72 of 131 homicides that year, for a true rate of 55 percent. For 2009, Lanier reported a rate of 76 percent, which would amount to about 110 of 144 cases. Records show that 67 of the 2009 cases, or 46 percent, were closed.
For 2008, a 75 percent closure rate was reported, but the department closed 91 of 186 slayings that year, for a true rate of 49 percent. And for 2007, Lanier reported a nearly 70 percent closure rate, but records show that 89 of the year’s 181 homicides were closed, for a rate of 49 percent.
“They’re fostering the false perception that they’ve accomplished something when actually what they’re doing is fudging their numbers,” said James Trainum, a longtime D.C. homicide detective who handled several high-profile cases.
Trainum said homicide closure rates are a political football in the District. “Careers rise and fall based on statistics,” said Trainum, who also investigated cold cases before retiring in 2010.
Wyndell C. Watkins Sr., a retired D.C. deputy police chief who headed the department’s homicide unit in the early 1990s, remarked: “The pencil has solved a lot of cases.”
David M. Kennedy, a professor and director of the Center for Crime Prevention and Control at John Jay College of Criminal Justice in New York, said it is “very confusing” to combine homicides from more than one year.
Kennedy said that most people think a closure rate “is a year’s killings that have been solved.”
Geoffrey P. Alpert, a professor of criminology at the University of South Carolina in Columbia, said there are no national standards or rules governing how to count closed cases, a situation that prevents criminologists from using such data for more sophisticated analyses.
The numbers are “more administrative than scientific,” Alpert said. “Across the United States, there’s no real best practices or criteria for measuring closed cases.”
Former FBI special agent Brad Garrett said the lack of federal standards allows police departments to put their own twist on the numbers with little or no oversight.
“Are there correct ways of doing it? Yes,” Garrett said. “If the case is from 1994, then you say that the rate includes X cases from 1994, X cases from 1996 and so on. That way it’s clear that it’s a combination from other years.”
Not ‘a realistic number’
Lanier’s 94 percent is “not even a realistic number” for a D.C. homicide closure rate, Garrett said, in part because many of the city’s homicides are stranger slayings, which are relatively difficult to solve.
A simple, single-year count was also endorsed by Isaac Fulwood Jr., D.C. police chief from July 1989 until September 1992, during which time homicides peaked at 482 a year.
“When the chief can stand up and say, ‘We’re closing 94 percent of the homicides,’ that is a powerful message,” said Fulwood, chairman of the U.S. Parole Commission. “That says something about the fact that the science has improved significantly. It says something about the homicide investigators. It says a whole lot.
“It’s important that the numbers be correct and that you always can prove it so that there’s no queasiness in the process.”
To give an accurate picture, “you need to adjust the numbers back,” Fulwood said. “I’d say, ‘Okay, if I’ve got a closure in 2011 of a homicide I should have closed in 2008, I’d go back and adjust the 2008 numbers. That way, there’s no sense that you’re trying to do something different.”
Pr. George’s and Baltimore
Prince George’s had 95 homicides last year and closed 51 of them, resulting in a 54 percent closure rate, records show. Police closed 12 more cases that occurred in other years, boosting the UCR closure rate to 66 percent.
Baltimore police closed 65 of the 196 homicides reported in 2011, a true closure rate of 33 percent. Add the 26 cases from previous years and the rate climbs to 46 percent, records show.
The national homicide clearance rate was about 65 percent in 2010, based on the multiyear totals reported to UCR. Rates for 2011 will not be available until the fall.
John C. DeCarlo, an associate professor of criminal justice at the University of New Haven, Conn., and a former police chief in Branford, Conn., said a 94 percent closure rate is difficult for any major urban police force to attain. The difficulty is compounded in a historically high-crime city such as the District, once known as the murder capital of the country.
“Ninety-four percent is a rate in an urban area that every police department should aspire to but it may not be a realistic goal,” DeCarlo said.
Ron Waldrop, former assistant chief of the Dallas police, was involved in more than 5,000 homicide investigations during his 40 years on the force. He said he hasn’t heard of a 94 percent closure rate since the 1960s, “when most of the murders were people who knew each other.”
“That’s unbelievable,” he said.
More from The Washington Post: