Ledwith 1984.

Methods	Setting: community, Scotland, UK Recruitment: newspaper advertisements for a smoker's advice centre
Participants	1839 smokers responding to offers of advice on stopping smoking
Interventions	No face‐to‐face contact ∙ No advice control ∙ Self‐help leaflet with standard letter ∙ Self‐help leaflet and offer of individual advice upon returning a questionnaire
Outcomes	Abstinence at 12 months (for 10 months or longer ‐ based on self‐report) Validation: attempt to obtain saliva for thiocyanate but not complete; data based on self‐report only
Notes	2 vs 1, self‐help 3 vs 2, effect of tailored advice Only 34% returned baseline questionnaire to initiate tailored component No information about contents of leaflet Borderline whether this counts as a structured self‐help programme
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Assigned at random"; method not described
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding (performance bias and detection bias) All outcomes	Low risk	Although attempts to get biochemical validation were unsuccessful, control group was unaware of other treatment assignments; no face‐to‐face contact was given, hence differential misreport was judged to be unlikely
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	16% lost to follow‐up Non‐respondents included as smokers