Crime is down for the seventh year in a row. That's what the final 1998 crime statistics the FBI released yesterday indicate. But behind the happy news is a melange of conflicting trends and disagreements about what all of it means.

"There is no one reason for the continued drop in crime," said Attorney General Janet Reno. "It's a combination of factors. It's more police officers on the streets, greater partnerships between law enforcement agencies, continued efforts to keep guns away from criminals and a balanced approach that includes prevention, intervention, punishment and supervision.

"The falling rate is wonderful news. But we must not become complacent."

President Clinton echoed Reno's warning, saying the decrease "shows we can indeed turn the tide on crime." But he added: "Even as crime falls, we must not let down our guard. That is why we must redouble our efforts to build on what works."

In the field of criminology there has been little in the way of hard data about why crime has dropped in the 1990s. Two studies this summer put to rest one theory--that the decrease in the number of 15- to 24-year-olds was responsible. Even adjusted for that demographic shift in the age group that historically commits a disproportionate number of offenses, crime still dropped, said criminologist Steven D. Levitt of the University of Chicago. A spirited debate continues about whether high incarceration rates in the United States are responsible. There is a consensus, however, that the overall downward trends conceal a more complicated picture.

"When we say crime is falling, that is nationally," said James Alan Fox, Lipman professor of criminal justice at Northeastern University. "Nationally we are at a 30-year low. A homicide rate at 6 (per 100,000) is as low as 1967. It is not true that homicides are at a 30-year low for all segments of the population in all areas. And in that overall crime trend, you miss a lot of the action."

Some of the pieces that get lost in the overall downward trend relate to the recent teenage shootings at schools in towns such as Littleton, Colo., or Conyers, Ga. There are several incongruities. First, these shootings grab headlines. A check of statistics reveals that juvenile crime is decreasing. Possibly because of the publicity these shootings bring, people say they feel less safe in suburbs. The 1998 figures show that there may be another reason why perceptions are not matching the overall statistics: Youth homicide rates are half of what they were five years ago, but twice as high as they were 15 years ago.

There are other anomalies. "The biggest drops in the '90s have been among young black males, where the biggest increases were during the crack era of the 1980s. There has not been much of a drop in the 1990s among white teenagers in suburban and rural areas," Fox said.

Another aberration in the overall downward trend has to do with small cities. In small cities across the nation, there were more murders last year. This was the only size of city--with a population of 10,000 to 24,999--where the murder rate went up. In larger cities and suburbs, the trend was all downward. While criminologists caution about making one year's uptick into a trend, the increase--about 4 percent--is notable.

Alfred Blumstein, a criminologist at Carnegie Mellon University, said he thinks the most significant trend in the 1998 Uniform Crime Reports was the drop in gun-related homicides. The total number of homicides decreased from 18,209 in 1997 to 16,904 in 1998--a drop of 1,295. The number of homicides in which a firearm was used declined from 10,729 in 1997 to 9,143 in 1998--a drop of 1,586.

"The decline in homicides were all accounted for by the decline in firearm homicides," said Blumstein. "I think it is an important observation. I think the variety of efforts that have been pursued in recent years to restrict access to firearms seem to be having some effect."

But are those efforts really responsible? With so little research in the area, it is difficult to reach a solid conclusion. Pennsylvania State University criminologist Darrell Steffensmeier and Federal Bureau of Prisons research analyst Miles D. Harer noted in an August article in the Journal of Research in Crime and Delinquency:

"The rise and now the sudden drop in crime rates offers a kind of natural experiment for investigating the macro forces that shape crime trends (especially because the trends are somewhat uneven across jurisdictions). Because it ranks as one of the most pressing theoretical and policy issues facing criminology/criminal justice today, the lack of systematic research on crime trends of the past decade or so is both surprising and disappointing."

Violence on the Decline

The overall trend in crime rates is still down . . .

All violent crime:

Approximately 1.5 million violent crimes were reported to the nation's law enforcement agencies in 1998, a decrease of 6 percent from the 1997 level and the lowest rate since 1987.

Murder and nonnegligent manslaughter:

An estimated total of 16,914 persons were victims of murder in the United States during 1998, a decrease of 7 percent from the 1997 level and the lowest rate since 1967.

But looking closely . . .

* Large cities experienced declines in murder, but small cities (those with populations between 10,000 and 24,999, a total of about 20 million people) experienced the only increase in murder volume -- 4 percent.

* The use of firearms in homicides is continuing to decrease, from 68 percent in 1997 to 65 percent in 1998.

* Youth homicide rates are half of what they were five years ago, but twice as high as they were 15 years ago.

And some things remain somewhat the same . . .

* The highest amount of violent crime occurs in August.

* February is the least violent month.

* Almost all (94 percent of black and 87 percent of white) murder victims are killed by a member of their own race.

* Males account for the overwhelming number of victims (75 percent) and known perpetrators (65 percent) of murder.

* Murders connected to the top 4 circumstances -- robbery, drug trafficking, arguments and juvenile gangs -- continued a trend of significant decline since 1994.

SOURCE: FBI

CAPTION: Attorney General Reno: "There is no one reason" for lower crime rates.