The Observatory shows for each year since 2011, the scientific articles of each university published in open and closed access.
Until 2021, the degree of openness has been calculated from data extracted from Web of Science and Scopus and using the Unpaywall. The dataset with the data 2011-2021 is published in CORA-RDR.
From 2023, data extracted fromOpenalex from ROR of each university.
After removing the duplicates, the DOI retrieves the number of items that:
- have been published in pure open access journals whether or not an APC has been paid (diamond journals)

- have been published in hybrid journals, ie subscription journals that offer authors to publish in open access immediately by paying a Article Processing Charge

- They have free access but the articles have no license: bronze

- They are only open in institutional or thematic repositories

- they are not in open access
Embargos imposed by publishers on articles deposited in repositories are not recorded as open until the embargo period has elapsed (normally 12 or 24 months).
When an article is published openly in a journal and in a repository it is counted only once, prioritizing publication in the journal and not deposit in the repository (Charts 1 and 2).
Instead, Graph 3 shows a column for each participating university and shows the availability of copies in repositories of the pure, hybrid, and bronze options.
The information is updated 2 times a year, during the months of April and October.