Table 1

Characteristics of available eligible studies

Authors, yearnStudy settingSampleLength of studyIntervention and intensity
Randomised control trials
 Palmgreen et al, 199116207USARandomly recruited 18–22 year olds in Fayette County, KentuckyImmediate post-testTwo anti-illicit-drug PSAs viewed twice over 10 min
 Fishbein et al, 2002223608USAMiddle and high school students from 10 American schoolsImmediate post-testSix anti-illicit-drug PSAs of a total of 30 viewed once
 Harrington et al, 200318338USA18–20 year olds recruited from a local college in Fayette County, Kentucky4 weeksFour PSAs viewed once a week for 4 weeks for a total of 16 exposures
 Yzer et al, 200321418USAStudents (mean age 14 years) from a middle school and a high school in PhiladelphiaImmediate post-testTwo anti-marijuana PSAs, two anti-‘hard’ drug PSAs and an anti-drug testimonial, two anti-marijuana and two anti-‘hard’ drug PSAs, or four anti-‘hard’ drug PSAs once
 David et al, 200623535USA7th- and 12th-grade students from 3 schools in PhiladelphiaImmediate post-test10 PSAs viewed once; participants then randomised to engage in online chatting immediately following viewing
 Czyzewska and Ginsburg, 200720229USAUndergraduate freshmen aged 18–19 in San Marcos, TexasImmediate post-test15 anti-marijuana or 15 anti-tobacco ads once
 Wagner and Sundar, 20081965 (Trial 1); 28 (Trial 2)USAHigh-school seniors aged 17–18 in Pennsylvania (Trial 1). Undergraduate students in Pennsylvania (Trial 2).Immediate post-testFour anti-illicit-drug PSAs once
Observational
 Palmgreen et al, 2002243174 (Fayette County); 3197 (Knox County)USAPublic school students aged 12–16 in Knox County, Tennessee and Fayette County, Kentucky32 months70% of sample exposed to a minimum of three anti-illicit-drug PSAs per week for 4 months
 Orwin et al, 200443142USAYouth aged 9 to 18 surveyed through the National Survey of Parents and Youth5 yearsAverage of 2.5 anti-illicit-drug PSAs viewed by sample over 58 months
 Pennay et al, 20065Pretest: 1400
Post-test: 1490
AustraliaYouth aged 13–20 recruited into a national survey of youth1 yearThree anti-illicit-drug PSAs over 9 weeks. Intensity not reported.
 Palmgreen et al, 2007254795 (Fayette County); 4803 (Knox County)USAPublic school students aged 13–17 in Knox County, Tennessee and Fayette County, Kentucky48 monthsFour antimarijuana PSAs. Intensity not reported.
  • PSA, public-service announcement.