Malott 1984.

Methods	Randomised controlled trial Study dates: Not stated. Worksite, USA
Participants	24 smokers, 17% male, mean age 34 yrs; mean number of cigarettes smoked per day 24 Partner: same sex, co‐workers % non‐smoking partner not stated
Interventions	(1) Standard controlled smoking: 6 weekly group meetings ‐ 50 minutes each (6‐week programme) (n = 12) (2) Controlled smoking + PS: 6 weekly group meetings, received Partners Controlled Smoking Manual, and monitoring booklets were used (6‐week programme) (n = 12)
Outcomes	Self‐report, lab analysis of spent cigarette butts, CO tests, and post‐treatment questionnaire. 6‐month follow‐up
Notes	Funded by Grant #30615 from the National Heart, Lung, and Blood Institute Author declarations: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Authors stated only that participants were randomly assigned "Groups were randomly assigned", and gave no further information about how the sequence was generated.
Allocation concealment (selection bias)	Unclear risk	Method not specified
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Self‐reported abstinence was verified with exhaled CO. We therefore judge the risk of detection bias as low.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 1 participant lost to follow‐up in the standard control group