Etringer 1984.

Methods	Study design: Randomized controlled trial Country: USA Recruitment: Community volunteers Group Size: 7 ‐ 13
Participants	72 smokers; 57% women, av. age 36, av. cpd 25 Therapists: doctoral candidates with 2 yrs in counselling psychology
Interventions	Factorial design using 2 cessation programmes and an intervention on group cohesiveness. Not clear whether session patterns identical for each. 9‐wk course of 45 ‐ 60‐min sessions 1. Enriched cohesiveness using written commitments, exercises and video. Satiation smoking in preparation for cessation 2. Enriched cohesiveness. Nicotine fading in preparation phase 3. Standard group. Satiation smoking 4. Standard group. Nicotine fading
Outcomes	Abstinence at 1 yr Validation by randomly contacting approx half of the 3 informants nominated
Notes	No non‐group control. 1&2 vs 3&4 in comparison 2.3. Originally treated as 2 studies in MA but due to small size now collapsed
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"For the most part, subjects were assigned to treatment on a random basis. However for logistical reason the requests of couples and friends who wished to be assigned to the same group were honoured"
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of outcome assessment (detection bias) All outcomes	Low risk	No validation but all participants had similar contact, likelihood of differential self‐report judged low
Incomplete outcome data (attrition bias) All outcomes	Low risk	No mention of losses to follow‐up, all recruited participants included in analyses