Scholars have been devoting more attention to older literature, a new study of the citation patterns in journal articles reveals.
The paper, “On the Shoulders of Giants: The Growing Impact of Older Articles,” by Alex Verstak and six employees of Google Inc. analyzed the age of citations from 1990 to 2013. They report that scholars are citing proportionally more of the older literature. Whats more, the trend appears to be increasing over time.
“Older articles” were defined as being 10 years old or older.
The researchers report that since 1990, the share of references to older articles has increased by 28%. Business, Economics & Management journals increased their share by 56%, and Computer Science by 39%. In contrast, Chemical & Material Sciences and Engineering both increased their share by just 2% and 3%, respectively.
The researchers explain their results by several changes in the way scholarly information is produced, disseminated, and discovered, including:
- A industry-wide transformation from print to online distribution
- Mass digitization of backfiles and journal archives
- Full text indexing, and
- Better search engines based on relevance ranking
While the results of this study are not novel (indeed, I covered several earlier studies on this topic several years ago), they are intuitive. For scholars, access to the literature has been been getting much, much easier– especially for older materials. As the effort required to identify and retrieve older literature declines, we should expect to see greater use of the older materials.
Most of us (publishers, software engineers, librarians, archivists, and scholars themselves) would accept the findings of this paper as good news, especially in a news cycle that focuses on negative stories (shrinking library funds, commercial publisher profits, licensing impasses, misuse of research funds, plagiarism and fraud in science, among others). We could all benefit from some good news. Everyone, please pat yourself on the back!
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.
Like the recent Google study of more highly-cited articles being published in non-elite journals, this research paper leaves out details that would allow me to make better sense of the data and ignores other factors that may explain their results. For example, there is no mention of article-level linking, facilitated by the Digital Object Identifier (DOI). While I understand that the authors of this study all work for a search engine company, for someone working in publishing or libraries, ignoring the DOI is a major omission.
Similarly, a lack of historical context makes the paper ripe for availability bias. The trend reported by the researchers begins in 1990, years before widespread use of the web and functioning relevance based search engines, like Google, and decades before Google Scholar debuted. Somehow, it feels like we’ve always had them. But 1990, you were likely to be using a 2400/bit modem. Feeling nostalgic? If you’re over 40, take short trip down memory lane with the sound of dial-up Internet.
During much of the 1990s, academic journals were print-based, although some publishers were experimenting with digital delivery. Internet connectivity was not ready to send large PDF files, so many early digital access to journal articles came on compact discs, arranged in towers or locked in deep library filing cabinets. Still, even in this exciting time of new tools, few publishers were looking backward into their archives. JSTOR would be the first major company to move into this void.
The first ‘Big Deal’ (bundled access to a publisher’s entire collection of articles) was introduced in 1996 by Academic Press, now part of Elsevier. It was several years before other publishers adopted similar package deals. When the library market became saturated, publishers diverted their attention to digitizing backfiles. Most of these mass digitization projects took place in the mid-2000’s.
My historical diversion is to point out that the trend to cite proportionally more older material has been going on for decades, as early as the 1960s, long before the Internet or digital publishing arrived. It is likely that these tools (along with email, Big Deals, mass digitization, article-level linking, repositories, and better search engines) are making it easier to find–and therefore cite–older relevant material; however, these new tools only explain the last little upward swing on Google’s chart.
Something much bigger is taking place.