In this paper, we examine the evolution of the impact of older scholarly articles. We attempt to answer four questions. First, how often are older articles cited and how has this changed over time. Second, how does the impact of older articles vary across different research fields. Third, is the change in the impact of older articles accelerating or slowing down. Fourth, are these trends different for much older articles. To answer these questions, we studied citations from articles published in 1990-2013. We computed the fraction of citations to older articles from articles published each year as the measure of impact. We considered articles that were published at least 10 years before the citing article as older articles. We computed these numbers for 261 subject categories and 9 broad areas of research. Finally, we repeated the computation for two other definitions of older articles, 15 years and older and 20 years and older. There are three conclusions from our study. First, the impact of older articles has grown substantially over 1990-2013. In 2013, 36 of citations were to articles that are at least 10 years old; this fraction has grown 28 since 1990. The fraction of older citations increased over 1990-2013 for 7 out of 9 broad areas and 231 out of 261 subject categories. Second, the increase over the second half (2002-2013) was double the increase in the first half (1990-2001). Third, the trend of a growing impact of older articles also holds for even older articles. In 2013, 21 of citations were to articles >= 15 years old with an increase of 30 since 1990 and 13 of citations were to articles >= 20 years old with an increase of 36 . Now that finding and reading relevant older articles is about as easy as finding and reading recently published articles, significant advances aren't getting lost on the shelves and are influencing work worldwide for years after.
The article presents the early findings of an exploratory deep log analysis of journal usage on OhioLINK, conducted as part of the MaxData project, funded by the U.S. Institute of Museum and Library Services. OhioLINK, the original “Big Deal,” provides a single digital platform of nearly 6,000 full-text journals for more than 600,000 people; for the purposes of the analysis, the raw logs were obtained from OhioLINK for the period June 2004 to December 2004. During this period approximately 1,215,000 items were viewed on campus in October 2004 and 1,894,000 items viewed off campus between June and December 2004. This article provides an analysis of the age of material that users consulted. From a methodological point of view OhioLINK offered an attractive platform to conduct age of publication usage studies because it is one of the oldest e-journal libraries and thus offered a relatively long archive and stable platform to conduct the studies. The project sought to determine whether the subject, the search approach adopted, and the type of journal item viewed (contents page, abstract, full-text article, etc.) was a factor in regard to the age of articles used. © 2006 Wiley Periodicals, Inc. Online journals promise to serve more information to more dispersed audiences and are more efficiently searched and recalled. But because they are used differently than print—scientists and scholars tend to search electronically and follow hyperlinks rather than browse or peruse—electronically available journals may portend an ironic change for science. Using a database of 34 million articles, their citations (1945 to 2005), and online availability (1998 to 2005), I show that as more journal issues came online, the articles referenced tended to be more recent, fewer journals and articles were cited, and more of those citations were to fewer journals and articles. The forced browsing of print archives may have stretched scientists and scholars to anchor findings deeply into past and present scholarship. Searching online is more efficient and following hyperlinks quickly puts researchers in touch with prevailing opinion, but this may accelerate consensus and narrow the range of findings and ideas built upon.