How often are older articles cited in scholarly papers and how is this changing over time? In the last two decades we have seen significant changes in scholarly communication. Scholarly journals have largely moved on-line, scientific publishers have digitized their archives to make the entire history of their publications available, and search services now index the entire text of articles instead of just abstracts and keywords. These changes should have made it easier for researchers to find the most relevant articles for their work regardless of the age of the articles. And in fact, the impact of older articles has grown substantially over 1990-2013.
Alex Verstak and collaborators at Google have studied(1) how often older articles are cited in modern papers and how his has changed since the advent of electronic publishing. Their analysis indicates that, in 2013, 36% of citations were to articles that are at least 10 years old and that this fraction has grown 28% since 1990. 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.
Well, that is the case for all areas of research except two broad ones: Chemical & Material Sciences and Engineering. Why citation trends differ in these two disciplines isn’t clear. Can you figure out why? I have no idea, but I must say it came as no surprise to me 🙂
I can only imagine what Santayana would have in store for them.
(1) Alex Verstak, Anurag Acharya, Helder Suzuki, Sean Henderson, Mikhail Iakhiaev, Cliff Chiung Yu Lin, Namit Shetty, “On the Shoulders of Giants: The Growing Impact of Older Articles”, November 4, 2014 arxiv.org/abs/1411.0275
Featured Image: The fire of Alexandria, woodcuts by Hermann Göll, 1876.