Consensus group methods are widely used in research to identify and measure areas where incomplete evidence exists for decision-making. Despite their widespread use, these methods are often inconsistently used and reported. Using examples from the three most commonly used methods, the Delphi, Nominal Group and RAND/UCLA; this paper and associated Guide aim to describe these methods and to highlight common weaknesses in methodology and reporting. The paper outlines a series of recommendations to assist researchers using consensus group methods in providing a comprehensive description and justification of the steps taken in their study.