|One or more security cameras to monitor the school||—||38.5||47.9||57.6|
|Security guards and/or assigned police officers||54.1||63.6||69.6||67.9|
|Other school staff or other adult supervision in the hallway||85.4||88.3||90.6||89.8|
|A requirement that students wear badges or picture identification||—||21.2||22.5||24.7|
|A code of student conduct||—||95.1||95.3||95.1|
|Locked entrance or exit doors during the day||38.1||48.8||52.8||54.2|
|A requirement that visitors sign in||87.1||90.2||91.7||92.7|
— Not available.
NOTE: "At school" includes the school building, on school property, on a school bus, and, from 2001 onward, going to and from school. In 2005, the unit response rate for this survey did not meet NCES statistical standards; therefore, interpret the data with caution. For more information, please see appendix A. Population sizes for students ages 12–18 are 24,614,000 in 1999; 24,315,000 in 2001; 25,684,000 in 2003; and 25,811,000 in 2005.
SOURCE: U.S. Department of Justice, Bureau of Justice Statistics, School Crime Supplement (SCS) to the National Crime Victimization Survey, various years, 1999–2005.