Google Trends: Opportunities and limitations in health and health policy research.

Web search engines have become pervasive in recent years, obtaining information easily on a variety of topics, from customer services and goods to practical information. Beyond these search interests, however, there is growing interest in obtaining health advice or information online. As a result, health and health policy researchers are starting to take note of potential data sources for surveillance and research, such as Google Trends™, a publicly available repository of information on real-time user search patterns. While research using Google Trends™ is growing, use of the dataset still remains limited. This paper offers an overview of the use of such data in a variety of contexts, while providing information on its strengths, limitations, and recommendations for further improvement.