Fig 1.
Journals listed on Beall’s list and their listing in different databases.
A, Venn diagram of ISSN overlaps between the ISSN database (yellow), PubMed (blue) and PMC (red) of all journals listed in Beall’s list. B, Venn Diagram of all ISSNs listed in the ISSN database (blue), DOAJ (grey), PubMed (yellow), Web of Science (green) or Scopus (pink) of all journals listed on Beall’s list.
Fig 2.
Characterization of Beall’s list in terms of country of origin and title geographical location.
A, Number of journals on Beall’s list per country as provided by the ISSN database. B, Linking of commonly used geographical descriptions in journal titles of journals on Beall’s list with country information provided by the ISSN database.
Fig 3.
Characterization of journals being listed on Beall’s list and their development over time (2011–2018).
A, Issued DOIs from 2011 to 2018 of all journals listed on Beall’s list in comparison to all journals listed in the DOAJ. Crossrefs data was used to retrieve the DOI count for each journal on Beall’s list or the DOAJ and put in direct comparison for the period of 2011 to 2018. B, Box plot of all DOIs issued by crossref over the years of 2011 to 2018 to journals listed on Beall’s list. C, Change of issued DOI count from year to year of journals listed on Beall’s list. From crossref’s data, it was calculated if a journal increased, decreased or had no change in their yearly article count compared to the previous year.
Fig 4.
Article count of publishers which were listed on Beall’s list in the time period 2011 to 2018.
A, Bubble plot of all publishers listed on Beall’s list, which had journals that had a continuous increase of issued DOIs over the last six to seven years. Size of bubbles represents the number of journals of the given publisher that had a continuous increase in issued DOIs over the last six to seven years as calculated from Crossrefs data. B, Line plot of the biggest publishers on Beall’s list with the total number of issued DOI count during the years 2011 to 2018. Article count information (DOI count) was retrieved from Crossref’s database and plotted for the period of 2011 to 2018 for the ten biggest publishers listed on Beall’s list.
Fig 5.
Characterization of journals being listed in the DOAJ and their development over time (2011–2018).
A, Box plot of all DOIs issued by crossref over the years of 2011 to 2018 of journals listed in the DOAJ. All journals that had more than 7,500 DOIs issued per year were labeled with their respective journal title. B, Change of issued DOI count from year to year of journals listed in the DOAJ. From crossref’s data, it was calculated if a journal increased, decreased or had no change in their yearly article count compared to the previous year.
Fig 6.
Article count of publishers which were listed in the DOAJ in the time period 2011 to 2018.
A, Bubble plot of all publishers listed in the DOAJ who had journals that had a continuous increase of article publications over the last six to seven years. Size of bubbles represents the number of journals of the given publisher that had a continuous increase in issued DOIs over the last six to seven years as calculate from crossref’s data. B, Line plot of the biggest publishers in the DOAJ with total number of issued DOIs during the years 2011 to 2018. Article count information (DOI count) was retrieved from Crossref’s database and plotted for the period of 2011 to 2018 for the ten biggest publishers listed in the DOAJ.
Fig 7.
Correlation between total citations and total published articles by journals listed on Beall‘s list in different internationally recognized databases.
Scatter plot of journals’ total citations and total issued DOIs from 2011 to 2018 divided by being listed in the DOAJ (A) and Web of Science (B). Country information of the ISSN database was combined with the DOI and citation count stored in the crossref and data stored in the different databases for journals listed on Beall’s list. Linear relationships between total citations and total articles published were assessed by Kendall rank correlation.
Fig 8.
Analysis of citations of articles published by journals listed on Beall‘s list in different internationally recognized databases.
Boxplots of journals listed in the crossref’s cited-by program and (A) median citation per article per journal divided by database listing, (B) Percentage of articles with more than 50 citations per journal divided by database listing and (C) Percentage of articles with zero citations per journal divided by database listing. The Mann-Whitney U Test was used to compare different types of citations count and if the journal was listed in the indicated database. Data are presented as mean ± SD. * = p<0.05; ** = p<0.01; *** = p<0.001 and **** = p<0.0001.