The Valley News analyzed records from three different national databases: the National Crime Victimization Survey, a 50,000-household survey conducted annually by the Department of Justice; the National Database of Child Abuse and Neglect, which contains records of confirmed abuse cases collected annually from state social service agencies by the U.S. Department of Health and Human Services; and the FBI Uniform Crime Reporting System/National Incident Based Reporting System based on state summaries of crime reports to local police departments. The newspaper supplemented these sources with information from state agencies in New Hampshire and Vermont.

The National Crime Victimization Survey asks about sexual assault types ranging from unwanted touching to rape, oral sex and sodomy. All of these crimes are included in our analysis.

Vermont and New Hampshire social service agencies define sexual abuse of a child to include lewd and lascivious conduct, molestation, sexual exploitation, rape, prostitution, pornography and incest.

The FBI uses two different formats to collect crime data from states and local police departments.

The Uniform Crime Reporting System collects information about rape, which is defined as sexual penetration of a woman. This definition was also used in the newspaper's analysis of rape reports over time to ensure that state and national figures are comparable.

The FBI's National Incident Based Reporting System separates sex crimes into a variety of types. The newspaper's analysis counted offenses categorized by authorities as forcible: fondling, rape, sodomy and assault with an object. How accurate are these statistics?

The statistics based on the databases are only as accurate as the numbers reported to the agencies that collect and record the data. Each database has limitations.

The National Crime Victimization Survey (NCVS) asks a random sampling of Americans about their experience with a variety of crimes, including sexual assaults. Other surveys suggest that some respondents are underreporting the assaults.

Every state differs in the kinds of child abuse that each investigates and reports to the U.S. Department of Health and Human Services. For example, Vermont is one of a handful of states in which child social services have a mandate to investigate all suspected incidents of sexual abuse. Most states, including New Hampshire, focus primarily on cases in which the abuser is also a child's caretaker.

Regarding the FBI databases, many states, including New Hampshire, are still working towards getting all local police departments to contribute information. (Currently, all Vermont departments participate.) Also, police departments may categorize sex crimes differently, though some states, such as Vermont, have conducted training and spot-checks to improve consistency of reporting.

— Kristen Fountain