Using Google to search for evidence: how much is enough? One center's experience.

The rise of powerful search engines (e.g., Google) make the searching for gray literature more feasible within the time and resources of a typical systematic review. However, there are no hypothesis-testing studies to guide us on how to conduct such a search. It is our belief that the "best practices" for incorporating Google searches might come from the collection of experiential evidence that users have had, from which can be drawn some tentative conclusions. It is our intention with this communication to relay our experience with Google searches for five projects and the lessons we think we have learned. We invite our systematic review colleagues to contribute their own experiences and thus to build up the experiential evidence about when and how to use Google as a search engine to supplement traditional computerized database searches.