We all want to hear that crime is down, but we shouldn't read too much into the Ventura County Sheriff's Department's latest numbers on aggravated assaults just yet.

The department is doing a hand-check of crime reports for 2006 and the first half of 2007 to see how much the reported 21 percent reduction in violent crime is due to law-enforcement efforts and how much is due to a change in crime record-keeping.

"Until we do a hand-check of what percentage (of the crime drop) is attributable to reporting compared to enforcement, it would be a mistake to put too much stock in those statistics," said Undersheriff Craig Husband on Thursday.

In the past, "simple-assault" crimes, in which a weapon was present but not used, was counted in the "aggravated assault" column.

Aggravated assault is when a weapon is present and used.

Since "simple assault" accounting is now separated from "aggravated assault" accounting, it is possible the reduction in crime is not as high as the latest crime statistics might indicate at first blush.

We do know, however, that the Sheriff's Department's focus, through a new anti-gang unit, on gang arrests and on taking gang leaders off the streets, has reduced gang crimes, Undersheriff Husband said.

Formed early this year, this very active anti-gang unit spends most of its time dropping in on known gang members, scanning police reports for gang-related crimes and, most importantly, putting criminals behind bars — a total of 77 between February and June.

Since the latest crime reports have shed light on record-keeping and statistics, it is important to note how they are a tool of law enforcement.

Undersheriff Husband explained that while midyear crime reports are a "report card for our efforts," of far greater value are year-end crime reports. Also valuable, he said, are month-to-month reports, which allow law enforcement to "attack blips" in crime.

Since the sheriff's territory — the unincorporated areas and contract cities of Camarillo, Thousand Oaks, Fillmore, Moorpark and Ojai — is divided into reporting districts, the reporting "can get very refined," Undersheriff Husband said. By knowing what crimes are being perpetrated in a particular area, the department can employ different strategies to stop it.

The property-crimes uptick, reported in the sheriff's latest crime statistics, is not in question. Those crimes include auto theft, burglary and larceny.

That statistic suggests an increase in substance abuse — particularly methamphetamine — since there is a "strong nexus" between it and property crimes, Undersheriff Husband said.

Easy targets — such as unlocked doors for cars and residences and open garages — are obviously the most vulnerable.

"People need to keep that in mind," said Undersheriff Husband. Individuals taking simple precautions to protect themselves and their property and reporting suspicious behavior go a long way toward reducing crime.

"It's a team effort," Undersheriff Husband said. "It happens all the time that an alert citizen gets information and then does something with it." He gave the example of a resident who reported a suspicious gardening vehicle at his neighbor's house. He knew the neighbor was on vacation and did not employ a gardener.

That one tip helped solve a string of area burglaries.

What all crime statistics reveal are the challenges society and law enforcement must face — together.