[From Academia.edu] On May 8, we announced the results of a year-long study of articles posted to Academia.edu. In the study, we asked whether posting an article to Academia.edu was associated with more citations. We found — after controlling for a number of factors and applying several statistical models — that a typical paper posted to the site received about 83% more citations than similar papers that were only available behind paywalls. This translated to about one extra citation every year for the median paper.
We announced the results of the study on our home page, and it was covered by Fortune Magazine. More importantly, we put all of our data and code online. Anyone could — and still can — download our data and code, and easily replicate or modify any part of our study.
The study generated some discussion. A week after our announcement, Phil Davis published a blog post raising some questions about our data sample. He pointed out several “non-research” articles in our sample and asked whether the presence of these in the data might explain the result.
In response to that question, we have spent the last several weeks classifying the nearly 45,000 articles in our dataset, and identifying such “non-research” articles.
Today, we’re pleased to announce our revised study, which answers that question. Excluding any articles that we did not identify with high confidence to be original research or scholarship, we find a 73% citation increase associated with articles posted to Academia.edu. This is a little less in relative terms than the 83% we found in our original data, but amounts to approximately the same in absolute terms — about one extra citation every year for the median paper. We find a 64% citation increase to articles posted to Academia.edu compared with being posted on other open access venues, such as an open access journal, or a personal homepage (down from 75% in the original data).
The revised paper is available for download here.