Schinke 1981.

Methods	Design: individually randomized Location: not specified; investigators based in Seattle, WA (USA) Time frame: no information Sample size calculation (and outcome of focus): no information
Participants	General with N: 36 students in public high school Inclusion criteria: sophomore class students Exclusion criteria: no information
Interventions	Study focus: preventing adolescent pregnancy Theory or model: cognitive and behavioral training; problem‐solving schema Intervention: cognitive and behavioral training (14 sessions of 50 min each); reproductive biology and contraceptive methods; guest speakers, audiovisual aids, Socratic discussion pretest, training, and post‐test training and post‐test Control: 2 groups; no training pretest and post‐test post‐test only Duration: 14 group sessions of 50 minutes each
Outcomes	Primary: "habitual contraception"; "greater protection at last intercourse"; "less reliance on inadequate birth control" (no definitions) Secondary: knowledge of pregnancy prevention (post‐test only); attitudes toward family planning Follow‐up: 6 months
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No mention
Allocation concealment (selection bias)	Unclear risk	No mention
Blinding of participants and personnel (performance bias) All outcomes	High risk	Presume no blinding of participants or providers; not feasible due to type of intervention
Blinding of outcome assessment (detection bias)	Low risk	Measures scored by 2 assistants not aware of study conditions or hypotheses
Outcome measures	High risk	Contraceptive use from self‐report Investigator communicated that contraceptive outcomes were based on reported behavior; did not request data due to age of study
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Loss to follow‐up: no mention
Other bias	Unclear risk	Analysis for cluster randomized trial: NA