Mark Twain is often quoted for saying, "There are lies, damned lies, and statistics."

On that same note, there are a few things to keep in mind when looking at Uniform Crime Report statistics.

In 1929, the International Association of Chiefs of Police identified a need for reliable, uniform crime statistics on a national level.

The following year the FBI began collecting, archiving, and publishing the statistics they received from various law enforcement agencies.

Today, those statistics are known as the Uniform Crime Reporting program and are the basis for a number of publications such as "Crime in the United States" and "Hate Crime Statistics."

The UCR data is used by both local law enforcement agencies and the FBI to track crime and identify regional or local patterns and trends.

However, even the UCR program's Web site adds a disclaimer to the information offered, warning users the data is not intended to be, nor is it, an adequate measuring stick for a local law enforcement agencies' effectiveness.

"Since crime is a sociological phenomenon influenced by a variety of factors, the FBI discourages data users from ranking agencies and using the data as a measurement of law enforcement effectiveness," warns the site.

To ensure uniformity in reporting, the UCR program provides agencies with a handbook containing set definitions for offenses such as murder, rape, robbery, assault, burglary, motor vehicle theft, arson and larceny. This is necessary because certain offenses vary from state to state.

For example, under Nevada law, if a person were to give illicit drugs to another person and the latter person died, that would be considered murder.

By UCR standards, however, the offense does not qualify as murder, and as such, an incident of that nature would not be listed as a murder in the area's UCR stats.

The same goes for burglary versus larceny: By state standards, stealing something from Wal-Mart could be considered burglary in Nevada but would be listed as a larceny by UCR standards.

Although law enforcement agencies are not required to participate in the program, there is an estimated 99 percent participation rate among agencies, and the UCR Web site reports 17,000 agencies participating across the country in a given year.

UCR statistics cover states, metropolitan statistical areas, cities with over 10,000 inhabitants, suburban and rural counties, and colleges and universities.

The UCR also tabulates clearance rates, which is the number of crimes for which a specific suspect or suspects has been developed.

In order to mark a crime as cleared, enough evidence has to be acquired for law enforcement agents to make an arrest or pursue possible charges.

As such, a crime can be listed as cleared even if the suspect is not actually caught.

There are exceptional clearances as well, for example, when a suspect leaves the country or dies.