Figuring out whether Omaha is becoming a more or less safe city might be more complicated than the two mayoral candidates would lead voters to believe.
The crime statistics that have become a major point of contention over the past week show a city that has generally followed national trends, with a decades-long decline in crime that might have begun to taper off in recent years.
But City Councilwoman Jean Stothert, who is challenging Mayor Jim Suttle, has painted a very different picture of the city's situation, suggesting that it's become less safe than when Suttle took office four years ago.
Suttle has pointed to long-term trends showing that crime has declined or remained flat. But after arguing for the long view, the mayor then cited new quarterly crime data as evidence of improvement.
Both candidates' positions are grounded in data compiled by the Omaha Police Department and the FBI.
Experts, however, say the decisions about which pieces of information to use, both in terms of the number of years studied and the types of crimes, can have a major impact on the overall perception of the problem. Piecing together small snapshots of trends, as both candidates have done in the past week, doesn't tell the full story about what's happening with crime — or whom to blame or praise for the changes.
“Look at things like trends in the weather,” said Ryan Spohn, the director of the Consortium for Crime and Justice Research at the University of Nebraska at Omaha.
If you take April 2013 compared with April 2012, for instance, the average temperature might be 30 or 40 degrees colder, Spohn said.
If you want to look at how much crime went down for those months, he said, “one short comparison might be impressive, but the more you carve it up, the less of a story it is.”
From a distance, the story in Omaha generally lines up with a downward trend in crime that's been happening across the U.S. since the early 1990s.
Though criminologists believed the trend line would start heading back up as the country plunged into a recession, the downward slope continued through the latter part of the past decade. Statistics from the FBI's Uniform Crime Report, which compiles data from law enforcement, and the U.S. Department of Justice's National Crime Victimization Survey, which relies on surveys of crime victims, show the same overall decline in crime.
Through the recession, social scientists were surprised to find that the downward trend continued across the United States.
That was also the case in Omaha, where the number of property crimes declined each year in the decade between 2002 and 2010, ending up 35 percent lower than the high point in 2001.
Violent crime numbers of the last decade generally were at their lowest during the recession years but began rising in 2011.
Spohn said researchers aren't sure what caused the steady downward trend. Some point to higher incarceration rates, broader social assistance programs and improved law enforcement techniques and technology.
“The fact that there wasn't a spike in crime from the recession is probably related to those same factors that were causing a long-term drop in crime, which are still being debated,” he said.
Because the FBI has only released national data through the middle of 2012, measuring current trends is more challenging.
But both Stothert and Suttle have pointed to recent numbers to illustrate their positions.
Stothert made her case on two key statistics: a 9.7 percent uptick in violent crime in Omaha between 2010 and 2012 and a 10.6 percent increase in property crime in the same period. Her campaign also cited a 37 percent increase in murders, though that was from a different period: 2009 to 2012.
The numbers are accurate. But Christopher Uggen, a sociology professor at the University of Minnesota, warns that when using data from relatively low numbers of crimes, there's plenty of room for different interpretations. Pick a slightly different set of parameters, and the figures can change dramatically.
Change the comparison years from 2007 to 2012, for example, and crime in Omaha appears to be down across the board: violent crime by 3.6 percent, property crime by 7.2 percent and murder down by 2.4 percent.
Suttle's effort to use quarterly crime data to show trends comes with a similar caution.
Last week the mayor pointed to data that showed a drop in violent crime of 4 percent and overall crime of 3 percent in the first quarter of 2013, compared with the same period in 2012.
But similar comparisons could lead to conclusions that fall far from reality.
The data for the fourth quarter of 2012, for example, show that the number of murders had gone up by 50 percent from a year earlier. In reality, though, the number of murders dropped between 2011 and 2012, from 43 to 41.
“It's much better to take a longer view,” Uggen said. “To say, perhaps there are some disturbing trends here we have to take care of and address, but the big picture is that we've managed to do a good job with public safety.”
Both Spohn and Uggen said it's also hard to tie immediate changes to relatively new policy changes.
“In my view, it clearly makes a difference what chiefs of police and what mayors do — I would never discount that,” Uggen said.
“But I will say that the magnitude of that difference is very hard to calibrate. So often cities will take radically different approaches and claim that their approach was very successful, when all the cities around them enjoyed the same drop in crime,” he said.
And if broader, nationwide issues such as incarceration rates or even the overall age of the population are behind the longer trends, Spohn said it's even more difficult to know exactly how much of an impact a particular government official has had or will have on crime in a city.
“A lot of the things I'm talking about aren't things politicians can immediately and directly manipulate,” he said. “Not to leave them off the hook, but it's not as easy as making a decision and then crime will go down.”
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