[1] The authors described methodologies which do not involve direct elicitation of data from the research subjects.
Unobtrusive measures are contrasted with interviews and questionnaires, in that they try to find indirect ways to obtain the necessary data.
The unobtrusive approach often seeks unusual data sources, such as garbage, graffiti and obituaries, as well as more conventional ones such as published statistics.
Webb and his colleagues emphasize the importance of triangulating the results obtained through various methodologies, each with its own unique set of (usually unknown) biases.
The proliferation of digital media opened a new era for communication researchers in search of unobtrusively obtained data sources.