Exploring the h-Index at Patent Level Jian Cheng Guan School of Management, Fudan University, 670 Guo Shun Road, Shanghai, 200433, P.R.China. E-mail: guanjianch@buaa.edu.cn Xia Gao School of Management, Beijing University of Aeronautics and Astronautics, Beijing, 100083, P.R.China. E-mail: gaoxia1976@sina.com As an acceptable proxy for innovative activity, patents have become increasingly important in recent years. Patents and patent citations have been used for con- struction of technology indicators. This article presents an alternative to other citation-based indicators, i.e., the patent h-index, which is borrowed from bibliometrics. We conduct the analysis on a sample of the world’s top 20 firms ranked by total patents granted in the period 1996–2005 from the Derwent Innovations Index in the semiconductor area. We also investigate the relation- ships between the patent h-index and other three indi- cators, i.e., patent counts, citation counts, and the mean family size (MFS). The findings show that the patent h- index is indeed an effective indicator for evaluating the technological importance and quality, or impact, for an assignee. In addition, the MFS indicator correlates nega- tively and not significantly with the patent h-index, which indicates that the “social value” of a patent is in disagree- ment with its “private value.” The two indicators, patent h-index and MFS, both provide an overview of the value of patents, but from two different angles. Introduction Patents are becoming increasingly important to commer- cial organizations, especially major multinational compa- nies, in the knowledge economy. Patents provide a valuable source of information on technology development and inno- vative activity. It is crucial to analyze patent information to understand industrial trends and set future development directions. Fortunately, publications and patents as informa- tion carriers have many analogous features (author/inventor, institution/assignee, bibliographic referencing/patent-system referencing, bibliometric classification/official classification, Received November 12, 2007; revised August 4, 2008; accepted August 4, 2008 © 2008 ASIS&T • Published online 8 September 2008 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/asi.20954 references to scientific literature/references to patent or non- patent literature, statistical distributions of productivity or of citation/value, etc.; Bassecoulard & Zitt, 2004). Patent citation analysis seeks to link patents in the same way that sci- ence citation links the references in scientific papers (Karki, 1997). Patent citations allow the analyst to assess the quality and impact of cited material, as well as the linkages between cited and citing countries, between cited and citing compa- nies, and between cited and citing scientific and technological areas (Narin & Olivastro, 1988). The value of patents can be assessed in essentially the same way as the impact of scien- tific publication, i.e., by looking at the frequency of citations that a particular contribution receives from subsequent works (Harhoff, Scherer, &Vopel, 2003). This point received con- siderable support in Trajtenberg’s study of medical scanning devices (Trajtenberg, 1990). Recently in bibliometrics, a new measure, the h-index, has been proposed to capture a scholar’s productivity, which is simply defined as follows: “A scientist has index h if h of his or her N p papers have at least h citations each and the other (N p - h) papers have ≤ h citations each” (Hirsch, 2005). This measure has generated considerable interest (e.g., see Braun, Glänzel, & Schubert, 2006; Cronin & Meho, 2006; Egghe & Rousseau, 2006; Oppenheim, 2007; Saad, 2006) and attracted largely favorable comment (Ball, 2005; Bornmann & Daniel, 2007; Jin, Liang, Rousseau, & Egghe 2007). However, due to the disadvantages of the h-index in quantifying the scien- tific output of a scientist, a number of studies of corrections and complementary measures to the h-index have also been done (Egghe, 2006; Jin, 2006; Jin et al., 2007; Liang, 2006). It is worth noting that prior research pertaining to the h-index mainly focused on scientists, journals, disci- plines, and countries, based on scientific papers and paper citations. This article aims to introduce this simple new measure, the Hirsch index, into patent citation analysis. Based on patent citation analysis, many technology indicators have JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, 60(1):35–40, 2009