[Using consumer panels in public health observational studies].

Consumer panels are a market research method useful for gathering information about low-frequency or difficult-access customers. The objective of this field-note is to explain our experience using this method in a cross-sectional public health study on the use of electronic cigarettes. After taking into account other non-probabilistic sampling techniques to obtain a huge sample of electronic-cigarette users (n=600), in the end we decided to use consumer panels (recruiters) because of the relative short duration of the field work and the high representativeness of the sample.