Authorship Patterns Among Paper Mill-Related Retractions: Evidence from the Retraction Watch Database, 2000–2024

Recent studies have documented the decline of solo-authorship and the growing dominance of multi-authored publications in science. However, little attention has been paid to how paper mills may influence contemporary authorship structures. This study examines authorship patterns in 11,704 retracted publications classified in the Retraction Watch Database as paper mill-related and originally published between 2000 and 2024. The results indicate that multi-authored papers dominated the dataset overall (81.1%), while solo-authored papers accounted for 18.9% of all records and represented the single largest individual author-count category. Solo-authored records were substantially more prevalent among publications from 2020 to 2024 than in earlier publication periods, and were strongly concentrated among a limited number of publishers and publication venues. Although records classified as conference papers showed considerably higher levels of solo-authorship than non-conference records, this pattern was almost entirely concentrated within a single publication venue, the Journal of Physics: Conference Series. The findings reveal substantial heterogeneity in authorship structures among paper mill-related retractions, and show that some apparent differences are strongly shaped by publisher- and venue-specific concentrations. These results highlight the need for caution when interpreting aggregate authorship patterns in retraction data.