Participant characteristics
OSF
Of the 538 smokers referred by the research agency, 349 (65%) met the eligibility criteria, of whom 252 (72%) consented to participate and were randomized to one of the two study arms (Figure Consolidated Standards of Reporting Trials (CONSORT) flow diagramDemographic characteristics appeared comparable between participants who completed the study (Demographic and baseline smoking characteristics of participants.SD, standard deviation.HSI = Heaviness of Smoking Index (range = 0–6);MTSS = Motivation to Stop Scale (range = 1–7).Of the 4952 cigarette packs, 58 had at least one piece of information missing, either from the sticker or information relating to the cigarette type (brand variant, length or size). Of the 236 participants included in the primary analysis of the primary outcome, 12 had missing information imputed for the primary outcome. See the OSF registration for the protocol that was followed for handling missing information (The data that form the basis of the results presented here are available from the University of Cambridge Research Data Repository (