Background: Health care practice based on research evidence requires that evidence is synthesised, and that recommendations based on this evidence are implemented. It also requires an intermediate step: translating synthesised evidence into practice recommendations. There is considerable literature on evidence synthesis and implementation, but little on how guideline development groups (GDGs) produce recommendations. This is a complex process, with many influences on communication and decision-making, e. g., the quality of evidence, methods of presentation, practical/resource constraints, individual values, professional and scientific interests, social and psychological processes. To make this process more transparent and potentially effective, we need to understand these influences. Psychological theories of decision-making and social influence provide a framework for this understanding.Objectives: This study aims to investigate the processes by which GDGs formulate recommendations, drawing on psychological theories of decision-making and social influence. The findings will potentially inform the further evolution of GDG methods, such as choice of members and procedures for presenting evidence, conducting discussion and formulating recommendations.Methods: Longitudinal observation of the meetings of three National Institute of Health and Clinical Excellence (NICE) GDGs, one from each of acute, mental health and public health, will be tape recorded and transcribed. Interviews with a sample of GDG members at the beginning, middle, and end of the GDG's work will be recorded and transcribed. Site documents including relevant e-mail interchanges, GDG meeting minutes, and stakeholders' responses to the drafts of the recommendations will be collected. Data will be selected for analysis if they refer to either evidence or recommendations; the focus is on "hot spots", e. g., dilemmas, conflicts, and uncertainty. Data will be analysed thematically and by content analysis, drawing on psychological theories of decision-making and social influence
