The Rise and Rise of Citation Analysis

It is a sobering fact that some 90% of papers that have been published in academic journals are never cited. Indeed, as many as 50% of papers are never read by anyone other than their authors, referees and journal editors. We know this thanks to citation analysis, a branch of information science in which researchers study the way articles in a scholarly field are accessed and referenced by others (see box 1). Citation analysis is, however, about much more than producing shock statistics. Along with peer review, it has over the past three decades been increasingly used to judge and quantify the importance of scientists and scientific research. Citation analysis is also the machinery behind journal " impact factors " – figures of merit that researchers take note of when deciding which journal to submit their work to so that it is read as widely as possible. Indeed, the output from citation studies is often the only way that non-specialists in governments and funding bodies – or even those in different scientific disciplines – can judge the importance of a piece of scientific research. The Web has had a huge impact on citation-analysis research. Since the turn of the century, dozens of databases BOX 1: Citation Analysis at a Glance • Citation analysis, which involves counting how many times a paper or researcher is cited, assumes that influential scientists and important works are cited more often than others. • Although the ISI Science Citation Index has long been the most common tool for measuring citations in physics, other Web-based services are now challenging its dominance. • Each service produces slightly different results, revealing the importance of using several citation sources to judge the true impact of a scientist's work. • The Web is also leading to alternatives to the traditional " impact factor " of a journal or individual, including download counts and the h-index.