Violent crime in 2007 was down slightly nationwide, a trend that has been amplified in Philadelphia this year.

FBI statistics released yesterday show that throughout the United States last year, 1.4 million violent crimes were reported - 10,000 fewer than in 2006, or a drop of 0.7 percent.

The FBI defines violent crimes as murder, rape, robbery and aggravated assault.

In Philadelphia, the drop was greater. In 2007, there were 21,180 violent crimes, compared with 22,883 in 2006. That's a reduction of 1,703 individual crimes, or 7.4 percent.

Earlier this summer, the Philadelphia Police Department reported that murders were down about 20 percent for the first six months of this year. Today the number is about 21 percent, a spokesperson for Mayor Nutter said.

In Chester, violent crime was down by nearly 4 percent, while it rose 3.5 percent in Camden, FBI figures show.

Nutter and Police Commissioner Charles H. Ramsey have attributed the decline in violence in Philadelphia to the deployment of more police officers on the street, leading to a greater number of arrests, guns seized, and violent crimes cleared.

"Obviously a reduction in our rate of violent crime and homicides demonstrates that we are moving in the right direction," Nutter said through a spokesman. "However, both Commissioner Ramsey and myself recognize that we have further to go, and we are committed to taking the steps necessary to make Philadelphia a safer city."

Responding to the decrease in Philadelphia, Ralph Taylor, professor of criminal justice at Temple University, said, "Any time crime isn't going up is good news. There's a downward blip nationally and Philadelphia is going down. That's nice."

But, he added, the vagaries of criminal behavior are so complex that if people say they can completely explain crime trends, "they don't know what they're talking about."

While the reduction is good news, homicides in Philadelphia did increase by 23 percent between 2004 and 2006, something that should not be forgotten, according to Jeremy Travis, president of John Jay College of Criminal Justice in New York City.

"That 23 percent increase was stunning," said Travis, who testified on crime before the U.S. Senate Judiciary Committee last week.

He added that in that context, "Philadelphia's drop between 2006 and 2007 is not a very big one. You have to have a larger window to talk about trends."

Similarly, Travis said, the 0.7 percent national drop in violent crime in 2007 means very little.

It's nothing like the end of the 1990s, he said, "when we saw a 40 percent decline in homicide rates by 2000," attributable, he believes, to the easing of the crack epidemic and the advent of good economic times.

Since 2000, various cities such as Philadelphia have seen significant rises and falls in violent crime. "But in the aggregate," Alfred Blumstein, a criminologist at the Heinz School at Carnegie Mellon University in Pittsburgh, said yesterday, "the crime rate has been impressively flat as a national rate."

From 2000 to 2007, for example, the homicide rate per 100,000 population has hovered between 5.5 percent and 5.7 percent, Blumstein added.

There have been only minor fluctuations year to year in this century, he added, saying the 2007 drop in violent crime means very little.

Trying to explain criminal patterns, Richard Rosenfeld, criminology professor at the University of Missouri, St. Louis, said he believes that the economy greatly affects the crime rate.

Robberies and homicides increase during hard times, Rosenfeld said, adding that the current FBI figures do not reflect the sharp and sour current economic downturn.

Because of this, Rosenfeld criticized the law-enforcement community for slow reporting of crime statistics.

"It's frustrating to be learning about 2007 crime figures at the end of 2008," he said.

"We always have a pretty good picture of producer prices, consumer prices and other economic indicators month by month. There is no technical reason for the delay in crime information."