Reference Rot in the Repository: A Case Study of Electronic Theses and Dissertations (ETDs) in an Academic Library

This study examines ETDs deposited during the period 2011-2015 in an institutional repository, to determine the degree to which the documents suffer from reference rot, that is, linkrot plus content drift. The authors converted and examined 664 doctoral dissertations in total, extracting 11,437 links, finding overall that 77% of links were active, and 23% exhibited linkrot. A stratified random sample of 49 ETDs was performed which produced 990 active links, which were then checked for content drift based on mementos found in the Wayback Machine. Mementos were found for 77% of links, and approximately half of these, 492 of 990, exhibited content drift. The results serve to emphasize not only the necessity of broader awareness of this problem, but also to stimulate action on the preservation front.