The information about the FBI, its staffing and criminal enforcement efforts, was compiled by TRAC from a variety of sources. The sources included computerized data obtained under the Freedom of Information Act from the Justice Department and from the United States Office of Personnel Management. These data were supplemented by interviews with current and former government officials, attorneys, and agency data processing specialists.

Additional information was drawn from internal administrative records and hardcover publications of the Federal Bureau of Investigation; internal administrative records and statistical reports of the Justice Department; electronic databases, internal records and hardcover publications of the Administrative Office of the United States Courts; internal records and published reports of the Office of Personnel Management; electronic databases and report of the U.S. Congress; internal records and published reports of the General Accounting Office; and county-level and geo-based files from the United States Census Bureau, the Federal Deposit Insurance Corporation (FDIC), and the American Medical Association (AMA).

This section on "About the Data" provides information about the following topics. Choose from the following links for further details on each of these topical areas. (For help in finding data on your particular community or locale, see help about geography.)

Judging the Quality of Government Data: general information about how to judge the quality of government statistics, and what steps TRAC uses to assess the quality of data it receives.

Understanding the Terminology which Agencies Use: specialized terminology used by these agency sources in categorizing their activities.

Data Coverage: what the agency's databases were designed to cover and how these activities were recorded.

TRAC's efforts to obtain FBI information date back to 1990. However, the FBI has not been cooperative in providing TRAC access to statistics or record systems it maintains tracking its personnel and enforcement activities.