Data Value Talk

Just before this summer the U.S. Department of Justice filed a report about the FBI Terrorist Watchlist. This watchtlist serves as a critical tool for screening and  law enforcement personnel for alerting them when they come across a known or suspected terrorist. It is used by personnel at airports, harbours and the borderline. Also when you apply for a visum you are matched against this watchlist. The Terrorist Screening Center, a subsidiary of the FBI, is responsible for maintaining the watchlist.

This watchlist was created in 2004 from several other lists and at that time it consisted of about 68.000 entries. I use the word entries, because in the years after it became fuzzy if one record is the same as one individual. By the end of 2008 the list had grown to over 1,1 million entries. In 2008 after the American Civil Liberties Union (ACLU) mentioned that the list had passed the 1 million, the government came with an explanation. Although we have recorded over 1 million entries in the database, the net result is that these records correspond to about 400.000 individuals. Terrorist often use different and thus multiple identities, use several (falsified) passports etc. But adding entries with only the first initials and last name, while an entry of the full first names and last name already exists will result in unwanted side-effects. (more…)