Konstantina Delli1, Christos Livas2, Pieter U Dijkstra1,3. 1. Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. 2. Department of Orthodontics, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands. 3. Department of Rehabilitation, Center for Rehabilitation, University of Groningen, University Medical Center, Groningen, The Netherlands.
Abstract
Objective: As journal impact factors (IFs) can be artificially inflated by excessive journal self-citation practices, research quality evaluation based solely on IF ranking may be manipulated and, therefore, ethically challenged. This study aimed to analyze the longitudinal development of journal self-citation rates (SCRs) and IFs in dental literature and to determine possible confounders. Methods: Twenty-eight journals with scope within general dentistry and (sub)specialties listed in 1997-2016 Journal of Citation Reports® were scrutinized. The following information was retrieved: publication year, total number of citations, number of self-citations, IF, corrected IF, and SCR. Results: Endodontic journals had the highest SCR (median = 35.3, IQR = 21.6-47.5), journals related to periodontics had the lowest (median = 14.7, IQR = 8.9-25.5). Periodontics had the highest IF (median = 2.1, IQR= 1.7-2.8) and general dentistry had the lowest (median = 0.9, IQR = 0.7-1.2). SCR significantly decreased over time (p < .0001) by 1 unit per year. Additionally, 1 unit increase in corrected IF resulted in 15.2 units decrease in SCR. IFs significantly increased 0.06 units per year (p < .000).Conclusions: Overall, favourable changes in citation metrics have been observed for dental journals during the 20-year observation period. SCR significantly decreased per observation year whereas IFs significantly increased, indicating a healthy publishing environment in the dental literature. SCR was regulated both by time and corrected IF.
Objective: As journal impact factors (IFs) can be artificially inflated by excessive journal self-citation practices, research quality evaluation based solely on IF ranking may be manipulated and, therefore, ethically challenged. This study aimed to analyze the longitudinal development of journal self-citation rates (SCRs) and IFs in dental literature and to determine possible confounders. Methods: Twenty-eight journals with scope within general dentistry and (sub)specialties listed in 1997-2016 Journal of Citation Reports® were scrutinized. The following information was retrieved: publication year, total number of citations, number of self-citations, IF, corrected IF, and SCR. Results: Endodontic journals had the highest SCR (median = 35.3, IQR = 21.6-47.5), journals related to periodontics had the lowest (median = 14.7, IQR = 8.9-25.5). Periodontics had the highest IF (median = 2.1, IQR= 1.7-2.8) and general dentistry had the lowest (median = 0.9, IQR = 0.7-1.2). SCR significantly decreased over time (p < .0001) by 1 unit per year. Additionally, 1 unit increase in corrected IF resulted in 15.2 units decrease in SCR. IFs significantly increased 0.06 units per year (p < .000).Conclusions: Overall, favourable changes in citation metrics have been observed for dental journals during the 20-year observation period. SCR significantly decreased per observation year whereas IFs significantly increased, indicating a healthy publishing environment in the dental literature. SCR was regulated both by time and corrected IF.