Availability and Audit of Links in Altmetric Data Providers: Link Checking of Blogs and News in Altmetric.com, Crossref Event Data and PlumX

The aim of this paper is to compare and analyse the availability of blogs and news links from the three most important altmetric data providers (Altmetric.com, PlumX and Crossref Event Data, CED). In addition, the study explores the distribution of events by creation year in order to observe the coverage of old and new events. Researchers extracted 51,000 links from news and blogs from those providers. Those links were analysed with a link checker (Xenu’s Link Sleuth), and the statuses of those links in 2019 January were at the center of the study. The results show that 35.6% of news in Altmetric.com are not accessible and 28.9% of blog mentions in PlumX point to a broken link. These worrying percentages of broken links are due, mainly, to the employment of third parties to supply news and blog events. Altmetric.com is the service that provides a better-balanced distribution of events, while PlumX and CED group their events around the last two years. The study concludes that these aggregators need to develop a specific policy to improve the audit of these data for research evaluation processes (saving a copy of the event, employing more frequently crawls, avoiding external providers, etc.).