1. the process of collecting data about a person from a close source, rather than directly from the subject. An example is asking an individual to report on the job satisfaction of his or her partner.

2. the use of mechanical means, such as video surveillance or audiotaping, to record behaviors as a substitute for real-time observation and questioning by a researcher. In marketing research, an example would be the use of surveillance cameras to monitor shopper behavior in stores. This would cost less than paying a trained researcher to observe and interview shoppers in situ. There is also the advantage that such data can be viewed, stored, and analyzed at the researcher’s convenience.