Validation of database search terms for content analysis: The case of cancer news coverage

While databases are increasingly used for content analyses in mass communication and journalism research, concerns about sampling error have been largely ignored. We introduce a method to measure the quality of a search phrase according to two criteria: recall (its ability to accurately call up items of interest) and precision (ability to avoid extraneous ones). We present a detailed description of the evaluation procedure, offer an example of its use assessing an online search for news reports about cancer, and discuss limitations of the procedure and further potential uses.