"Drug testing of students is more prevalent in schools where drugs are used, kept or sold than in schools that are drug free. While only 23 percent of drug-free schools drug test students, 38 percent of non-drug-free schools conduct some type of drug testing.
"Drug testing is not associated with either significantly lower risk scores or lower estimates of student body drug use. The average risk score of teens attending a school that is not drug free but has drug testing is 1.69; the average risk score of students at non-drug-free schools without drug testing is 1.50. The estimate of students using illegal drugs averages 40 percent for non-drug-free schools with testing and 34 percent at non-drug-free schools without testing."

Source

QEV Analytics, "National Survey of American Attitudes on Substance Abuse VIII: Teens and Parents" (New York, NY: National Center on Addiction and Substance Abuse at Columbia University, August 2003), pp. 20-21.
http://www.casacolumbia.org/a…