Contents of this document on the methodology of barometer surveys, and more specifically the 2014 Health Barometer: A telephone survey using a random sample, Survey frame, Inclusion of households on the red or orange list, Inclusion of households with only a mobile phone, Inclusion of households with full unbundling, Description of the sampling procedure, Sample of households reachable via a landline number, Sample of households with only a mobile phone and unbundled households not reachable via a landline number, Survey scope, eligibility, and selection, Fieldwork, Questionnaire, Data analysis, sample profiles, The samples obtained, Characteristics of the different samples, Oversamples in nine regions, Probability of inclusion and weighting, Probability of inclusion, Weighting, Analysis methods and interpretations, Bibliography. The Health Barometers were created in the early 1990s. For nearly twenty years, these epidemiological surveillance surveys have made it possible to track the main behaviors, attitudes, and perceptions related to risk-taking and the health status of the population residing in metropolitan France: smoking, alcohol use and use of other drugs, vaccination practices, sexual behavior, cancer screening, physical activity, nutrition, quality of life, sleep, accidents, pain, healthcare utilization, mental health... They make it possible both to study the determinants of these various topics and to consider them themselves as determinants of the population’s health status. In this respect, they are very useful tools for the implementation of public health initiatives as well as for their evaluation. By their very nature, the Health Barometers are designed to be repeated over time, using the same methodology and questionnaire, in order to track changes in key health-related behaviors and attitudes. It is this commitment to methodological consistency that has guided the use of telephone surveys since the first Health Barometer, even though recent developments in telecommunications in France have led to significant adjustments, which will be described in detail in this chapter. Thus, the 2014 Health Barometer was designed with the aim of refining certain methodological elements to enhance their relevance.