Understanding Crime Data and Statistics

Crime Data and Statistics

The majority of crime data exists in the form of statistics. While many people take statistics to be "objective", no data speak for themselves. All data, statistical or otherwise, have limitations and can be interpreted in a number of different ways. A solid understanding of crime requires a critical understanding of crime data (e.g., we should always ask: where does the data come from? Who collected the data? What are its limitations?).

Types of Crime Data

Official crime data = data collected by government agencies (e.g., FBI and the Justice Department).

• Uniform Crime Reports (UCR)
• National Crime Victimization Survey (NCVS)

Unofficial crime data = nongovernmental data usually collected by private agencies and researchers, etc.

• Self-report studies (include questionnaires, interviews, etc.)

All sources of data (official and unofficial) have advantages and disadvantages.

Uniform Crime Reports (UCR)

Best known and most widely cited source of official crime statistics. Began in the 1930s. Submitted voluntarily by police departments throughout the US and compiled annually by the Federal Bureau of Investigation (FBI). Today over 17,000 police agencies across the United States (serving roughly 97 percent of the US population) participate in the UCR. A crime becomes "official" to the police only if the victim or witness reports the crime. Rather than focusing on all crimes, the UCR focuses on a relatively small number of crimes that are divided into two categories: Part I crimes and Part II crimes.

UCR: Part I Offenses (or Index Crimes)

• Homicide
• Forcible Rape
• Robbery
• Aggravated Assault
• Burglary
• Larceny-Theft
• Motor Vehicle Theft
• Arson

Also referred to as "index crimes". Considered the "most serious" crimes by the FBI. Data on Part I offenses include the number of offenses and the offense rate per 100,000 population (also known as "crime rate").