7 MedLine, the Social Science Citation Index<sup>6</sup> (SSCI), and SCOPUS<sup>7</sup> . These vary along key dimensions, one fundamental one being whether the database employs a classification system that allows us to make a credible distinction between ―health economics‖ publications and others.<sup>8</sup> Many databases do not pass this test for any plausible definition of ―health economics‖. MedLine, for example, includes hundreds if not thousands of articles that would be classified as ―economics‖ using the MeSH major topic. But many—if not most—have no economic analysis in them to speak of, and are written by people who quite probably would never claim to be an economist. SCOPUS and the SSCI are the other extreme. In SCOPUS, articles are classified as either ―economics, econometrics and finance‖ or ―health sciences‖ (but not both). SSCI does permit cross-classifications but trying to pin down ―health economics‖ results in a very narrow set of articles. Limiting publications to those that are classified as (a) ―economics‖ and (b) either ―health policy and services‖ or ―health care sciences and services‖ results in just 2,201 publications, all of which are in just six journals: Value in Health, Health Economics, PharmacoEconomics, the Journal of Health Economics (JHE), the European Journal of Health Economics, and the International Journal of Health Care Finance and Economics. This would be a very narrow definition of ―health economics‖ indeed. MedLine, SSCI and SCOPUS also all cover a limited range of publications. All three focus largely on journals, and MedLine focuses on medical journals and thus omits the core of the ―health economics‖ literature.

Because MedLine, SSCI and SCOPUS all lack a classification system that enabled us to separate out ―health economics‖ from other fields, and because they all have a limited coverage of publications, we decided to look instead to EconLit as the source of our bibliographic metadata on health economics publications—the same data source used by Rubin and Chang (2003). Its two big advantages are its scope and its JEL classification scheme. The number of titles has increased steadily since 1969 when the database started. EconLit now includes over 750 journals ―with substantial economics content‖. It has also included books, book chapters and doctoral dissertations since 1987, and for several years has also included working papers through

> 6 SSCI covers primarily journal articles and is limited to about 2,500 social science journals. Details of coverage are to be found at http://thomsonreuters.com/products_services/science/science_products/a-z/social_sciences_citation_index. 7 SCOPUS covers over 18,000 titles covering all disciplines including 16,500 peer-reviewed journals, as well as some book - chapters, including the North-Holland handbook series. Details of the database are to be found at http://info.scopus.com/scopus <u>in-detail/facts/.</u>

> 8 Alternatively we could have ignored the database‘s classification system and tried to classify publications on the basis of the words in titles, abstracts, and keyword lists. This would have been very laborious and would likely have caused us to end up with lots of errors of omission and commission.