But police attributed much of the increases to overall growth in the area. For example, reports of thefts in Orland Park, the largest and one of the fastest growing southwest Cook County suburbs, rose 4.1 percent. Some experts warn, however, that the numbers tell an incomplete story. By definition, the tally does not include unreported crimes. Some victims are unwilling to come forward, perhaps out of a reluctance to contend with the justice system bureaucracy or a belief that police will be unable to solve the crime, or even the desire to spare themselves embarrassment.
Experts say sexual assault, in particular, is widely underreported.
In areas with small numbers of reports, even a minor change can translate into a misleading jump or fall when expressed as a percentage. Figures also can be skewed because residents of one area may be far more likely to summon police for a given problem than those in another region. And the number of reports of crime can vary because of police policies, from starting a task force to crack down on particular offenses to presenting incorrect data. They want to show less crime for the most part. The crime rates in fast-growing communities also can be misleading because the true population might be larger than the figure used by the state.