	Introduction

Congress uses data from the Uniform Crime Reports (UCR), the National Incident-Based Reporting System (NIBRS), and the National Crime Victimization Survey (NCVS) to inform policy decisions and develop appropriate responses to crime. Because of the importance of crime data in both shaping policy and allocating federal funding, it is important to understand how each program collects data and the limitations of the data. This report reviews (1) the history of the UCR, the NIBRS, and the NCVS; (2) the methods each program uses to collect crime data; and (3) the limitations of the data collected by each program. The report then compares the similarities and differences of UCR and NCVS data. It concludes by reviewing issues related to the NIBRS and the NCVS. It was originally conceived as a way to measure the effectiveness of local law enforcement to provide law enforcement with data that could be used to help fight crime. UCR data are now used extensively by academics and government officials for research, policy, and planning purposes, and the data are widely cited in the media. The UCR also provides some of the most commonly cited crime statistics in the United States. However, the transition from the UCR to the NIBRS has been slow. Starting in the 1970s, consensus grew in the law enforcement community that the UCR needed to be updated to provide more in-depth data to meet the needs of law enforcement into the 21 st century. For each criminal incident, participating law enforcement agencies collect data on 53 different data elements, including data on the offense(s), the offender(s), the victim(s), the arrestee(s), and any property involved in the offense. The NIBRS does not use the UCR's Part I and Part II offense classifications. Group B contains 11 different offenses. National Crime Victimization Survey

The National Crime Victimization Survey (NCVS) is the primary source for information on the characteristics of criminal victimization and on the number and types of crime not reported to law enforcement. The NCVS has four major objectives: (1) developing detailed information about the victims and consequences of crime, (2) estimating the number and types of crimes not reported to police, (3) providing uniform measures of selected types of crimes, and (4) permitting comparisons over time and population types (e.g., urban, suburban, and rural). The survey asks respondents whether they have been the victim of
rape and sexual assault, robbery, simple and aggravated assault, purse snatching/pickpocketing, burglary, theft, or motor vehicle theft. In addition to estimating the number of annual victimizations, the NCVS also gathers data on the details of each victimization incident.
Crime data collected through the Uniform Crime Reports (UCR), the National Incident-Based Reporting System (NIBRS), and the National Crime Victimization Survey (NCVS) are used by Congress to inform policy decisions and allocate federal criminal justice funding to states. As such, it is important to understand how each program collects and reports crime data, and the limitations associated with the data.
This report reviews (1) the history of the UCR, the NIBRS, and the NCVS; (2) the methods each program uses to collect crime data; and (3) the limitations of the data collected by each program. The report then compares the similarities and differences of UCR and NCVS data. It concludes by reviewing issues related to the NIBRS and the NCVS.
The UCR represents the first effort to create a national, standardized measure of the incidence of crime. It was conceived as a way to measure the effectiveness of local law enforcement and to provide law enforcement with data that could be used to help fight crime. UCR data are now used extensively by researchers, government officials, and the media for research, policy, and planning purposes. The UCR also provides some of the most commonly cited crime statistics in the United States. The UCR reports offense and arrest data for 8 different Part I offenses and arrest data for 21 different Part II offenses.
The NIBRS was developed by the Federal Bureau of Investigation to respond to the law enforcement community's belief that the UCR needed to be updated to provide more in-depth data to meet the needs of law enforcement into the 21st century. The NIBRS collects data, including data on offense(s), offender(s), victim(s), arrestee(s), and any property involved in an offense, for 46 different Group A offenses and 11 different Group B offenses. Despite the more detailed crime data that the NIBRS can provide, nationwide implementation of the program has been slow, for a variety of reasons, including cost considerations.
The NCVS is the primary source of information on the characteristics of criminal victimization, and on the number and types of crime not reported to law enforcement. The NCVS has four major objectives: (1) to develop detailed information about the victims and consequences of crime, (2) to estimate the number and types of crimes not reported to police, (3) to provide uniform measures of selected types of crimes, and (4) to permit comparisons over time and population type (e.g., urban, suburban, and rural). The NCVS asks respondents whether they have been the victim of rape and sexual assault, robbery, simple and aggravated assault, purse snatching/pickpocketing, burglary, theft, or motor vehicle theft. In addition to collecting data on the number of victimizations, the NCVS gathers data on the details of each incident of victimization. This report will be updated as warranted.