Table 2.
Characteristics of the six “sound” trials
| Authors | Country | Study design | Sample size | Sample characteristics | |||
|---|---|---|---|---|---|---|---|
| Gender | Age range | Socioeconomic position | Ethnicity | ||||
| Allen et al, 1997w1 | USA | Randomised, controlled trial | I=342; C=353 | Male=15%; Female=85% | 14-15 years | Authors describe sample as “high risk,” with 54% living in one parent households and 46% living in two parent households | Authors report “black”=67% ; “white”=19%; “Hispanic”=11%; “other”=3% |
| Berrueta-Clement et al, 1984w2 | USA | Randomised, controlled trial | I=58; C=65 | Male=60%; Female=40% | 3-4 years | Authors describe sample as children from families of low socioeconomic status | Authors report sample to be 100% “black” |
| Campbell et al, 2002w3 | USA | Randomised, controlled trial | I=53; C=51 | Male=49%; Female=51% | 0-4 years | Authors state sample was “high risk” from “impoverished households” | Authors describe sample as all “African-American” |
| Hahn et al, 1994w6 | USA | Randomised, controlled trial | I=125; C=125 | Male=47%; Female=53% | 14-17 years | Authors describe sample as recruited from list of families receiving public assistance | Authors report “white”=15%; “black”=76%; “Hispanic”=7%; “Asian”=1%; “other”=2% |
| Hawkins et al, 1999w7 | USA | Controlled trial* | I (full)=156; I (late)=267; C=220 | Male=50%; Female=50% (approx) |
6-12 years | Authors note that more than 56% participated in National School Lunch/Breakfast program | Authors report “white”=44%; “African-American”=26%; “Asian-American”=24%; “native American”=5%; “other”=3%. |
| Philliber et al, 2001w10 | USA | Randomised, controlled trial | I=589; C=574 | Male=45%; Female=55% | 13-15 years | Authors report almost half of young people come from families with at least one unemployed adult | Authors report “African-American”=43%; “Caribbean-black”=3%; “Hispanic”=29%; “white”=5%; “Asian”=4%; “multiethnic”=14%; “other”=2% |
*This study began as a randomised, controlled trial: students within eight schools were randomised into intervention or control groups, and those in the intervention group received the programme for four years. At the end of four years, children in both the intervention and the control group received the programme for two years. Additional schools matched to the original eight schools were recruited into the study. Children in these schools formed a new control group.