Table 2. Studies included in the meta-synthesis: Methodological approaches.
| Study | Data sources | No. of analysed
publications |
Publication years | Definition of OA |
|---|---|---|---|---|
| Larivière and Sugimoto (2018) | Papers published between 2009 and 2017 that are indexed in WoS
and have a DOI, combined with Unpaywall |
12,683,296 | 2009 – 2017 | Gold and Green |
| Piwowar et al. (2018) | Random sample of recent journal articles indexed in WoS,
combined with oaDOI database |
100,000 articles | 2009 – 2015 | Gold, Hybrid, Bronze, Green |
| Bosman and Kramer (2018) | Full WoS database, combined with oaDOI database | 12.3 million articles
and reviews |
2010 – 2017 | Gold, Hybrid, Bronze, Green |
| Science-Metrix (2018) | All articles in WoS and Scopus, combined with 1science database
of OA articles |
13.2 million articles | 2006 – 2015 | "Gratis" OA (Gold, Green, Other) |
| Martín-Martín et al. (2018) | All documents with a DOI from WoS, Social Sciences Citation Index
and Arts & Humanities Citations Index, combined with GS |
2.6 million
documents |
2009 and 2014 | Gold, Hybrid, Bronze, Green |
| Jamali and Nabavi (2015) | First ten hits from queries of minor Scopus subject categories in GS | 7244 articles | 1996 – 2013 | Any full text accessible through GS
(Gold, Green, Other) |
| Khabsa and Giles (2014) | GS | Capture-recapture
approach |
No limit | Any full text accessible through GS
(Green, Gold, Other) |
| European Commission (2014) | Scopus, combined with searches of DOAJ, ROAR, OpenDOAR,
PubMedCentral, and other sources of freely downloadable papers |
513,753 articles | 1996 – 2013 | Gold, Green, Other |
| Gargouri et al. (2012) | Random samples of articles indexed in Thomson-Reuters-ISI,
combined with robot crawling web for OA full-texts |
107,052 articles | 1998 – 2006 and
2005 – 2010 |
Any full text accessible on the web
(Gold, Green, Other) |
| Björk et al. (2010) | Random sample of articles from Scopus, combined with Google
searches for OA full-texts |
1837 articles | 2008 | Any full text accessible on the web
(Gold, Green, Other) |
| Hajjem (2006) | CDROM version of ISI’s Science and Social Science Citation
Indices, combined with robot crawling of the web for OA full-texts |
1,307,038 articles | 1992 – 2003 | Any full text accessible on the web
(Gold, Green, Other) |