ATLANTA — Not accounting for 22,000 crimes can definitely improve a city's crime rate.

That was the case in Atlanta, where police recently revealed they were missing that many crime reports from a single year.

While the underreporting shocked many civilians, it was no surprise for those in law enforcement, who are well aware that agencies across the country lose or alter crime reports to burnish their widely reported crime statistics.

In New York, a police captain was accused of routinely downgrading crime reports so he'd look good in the eyes of his superiors. Philadelphia's Sex Crimes Unit dismissed as non-crimes several thousand reports of rape in 1999. And in Baltimore, an information technology worker quit in December over claims the city's crime reporting was wildly inaccurate.

"It's been a chronic problem," said Samuel Walker, a criminal justice professor at the University of Nebraska at Omaha who runs the Web site www.policeaccountability.org. "But then again, no one knows exactly how serious it is. There's no real accounting, no real auditing."

Police and experts say crime rates never are all that accurate, since the job of crime reporting is mostly left to the police themselves — and police are under constant pressure to show crime rates are dropping.

Even the FBI's national crime reports are known to be only vaguely accurate, since they too rely on reports from police.

"Criminologists have known for years that crime statistics are not reliable," said Robert Friedmann, a criminal justice professor at Georgia State University. The problem, Friedmann said, can be caused by pressure from politicians who want to put a good face on crime, or by officers who fear for their jobs. The solution may involve more independent assessments like Atlanta's.

For the most part, the public would only find out if crimes are being downgraded — or if incidents are tucked into a dark corner — when there's a scandal.

The exception is a department such as Atlanta's, which ordered an independent audit to come clean on its misreporting problem. Only a few other cities — including Boston and New Orleans — have done the same.