Pederson 1981.

Methods	Study design: Randomized controlled trial Country: USA Recruitment: Volunteers for a S‐H smoking cessation programme
Participants	40 smokers; 60% women, av. age 39, av. cpd 28
Interventions	1. Pomerleau & Pomerleau manual, an introductory session, followed by 1‐hr group meetings at 2 and 6 wks 2. Danaher & Lichtenstein manual and same schedule of meetings as 1 3. Waiting‐list control
Outcomes	Abstinence at 6 m for at least 3 m Validation: none
Notes	1&2 vs 3 in comparison 1.5. Described by the authors as a S‐H programme but the 3 meetings met criteria for a group programme
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomized, method not described. Participants switched between the 2 manuals because of scheduling constraints
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of outcome assessment (detection bias) All outcomes	High risk	No validation, waiting‐list control
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants included in ITT analysis