"Dealing with uncertainty has been an important and distinct topic for PBL Netherlands Environmental Assessment Agency (formerly MNP) and the Dutch National Institute for Public Health and the Environment (RIVM), in terms of analysis and communication. Acting responsibly with regard to this issue is important; particularly where policy analyses are concerned. Without adequate attention to the role and implications of uncertainty, the outcome of research and assessments may be of limited value and could result in incorrect policy decisions, with all the attendant consequences. However, the general public does not always appear in need of very detailed information in ‘documents full of subtle distinctions’. Consequently, information on uncertainty is not always considered relevant, understood, or even noticed. Thus, uncertainty remains an awkward issue and a challenge for the authors of policy reports. This Guide comprises hints and points of attention, as well as questions that researchers should try to answer when communicating about uncertainty (e.g. in written reports and presentations). It is not intended as a protocol; every situation is unique and demands its own approach. Thus, the Guide for Uncertainty Communication is intended to support the researcher/communicator in making well-considered choices. Communication on uncertainty regarding a particular study requires having a clear picture of why this communication is important and to whom it should be addressed. For this, the issues and concerns of the intended target audience(s) must be known, as well as all relevant uncertainties involved in the study and their possible effects on the results of the study. This involves serious reflection on certain topics, such as on where uncertainties originate, what significance and/or implications they have, if uncertainty may be reduced, on the context of the study, and on the manner in which uncertainty was dealt with in the study. The purpose of the study will strongly determine what uncertainty information would be relevant. For example, a study which primarily deals with the effects of policy measures will focus less on uncertainty about the severity of environmental problems than would be the case when a newly emerging environmental problem is explored. Addressing these questions, ideally, would provide a clear insight into all relevant aspects of uncertainty, which should be communicated effectively to the intended target audiences. This Guide is set up to support this process." (Preface, pages 4-5)