OF COURSE IMMEDIATE OA GENERATES MORE CITATIONS THAN DELAYED OA

Laakso & Björk are comparing immediate and delayed Gold OA, which means comparing different journals. Journals differ in both subject matter and quality, and one of the ways to try to equate them is to equate them for impact. So if you don’t equate them for impact, you are comparing apples and oranges; but if you equate delayed and immediate Gold OA journals for impact, you can’t compare impact for delayed vs. immediate Gold OA!

The right way to compare delayed vs. immediate OA is by comparing delayed vs. immediate Green OA, which compares articles published within the same journal and year. To do this one needs both the date of publication and the date the article was made Green OA. It is a bit harder to get the OA date, but we already have an approximation for articles inn the University of Minho repository. See Figures 2c and 3c, which show that Immediate Green OA articles have more citations than Delayed Green OA articles:

Gargouri, Yassine, Larivière, Vincent & Harnad, Stevan (2013) Ten-year Analysis of University of Minho Green OA Self-Archiving Mandate (in E Rodrigues, Ed. title to come) http://eprints.soton.ac.uk/358882/