Journal Suppressions in the 2015 JCR Data – Why So Few?
You may notice that far fewer journals have been suppressed from the JCR this year for excessive journal self-citation and citation stacking (18 in 2015 data vs. 39 in 2014 data). This fact will undoubtedly lead many to wonder why, and if Thomson Reuters has in fact made any changes to the analysis this year that would explain such a large decrease. This blog post will attempt to address those questions.
The process remains the same. Thomson Reuters analyzes the Science and Social Sciences editions separately for the most recent completed year of citation data (2015 in this case), and journals showing anomalous citation practices are suppressed for that same JCR data year. Suppressed journals are eligible to be re-listed the following year provided that the citation anomalies have resolved to a level where we can again publish a meaningful Journal Impact Factor that reflects the real use of the journal among the broader scholarly community.
Factors considered in the journal self-citation analysis are: total citations; Journal Impact Factor (JIF); rank in category (by JIF); proportion of self-citations in the JIF numerator; and the effects of journal self-citation on both the JIF and rank in category.
Regarding the citation stacking analysis: Again, no criteria changed for this year. Factors considered include: total citations; JIF; donor journal’s proportion of recipient journal’s total citations and JIF numerator citations; and concentration of citations exchanged in the 2-year JIF window. Please see our journal suppression slide presentation for additional information.
If nothing changed in our analysis, what might explain the decrease in journal suppressions? One major factor is that we saw a significant decrease in candidate cases of citation stacking this year, particularly in the Social Sciences edition, which in turn led to far fewer confirmed citation stacking cases for the final suppression list.
Similarly, we saw a decrease in self-citation candidate cases in 2015 data relative to 2014. We also observed an overall downward trend in self-cite percentage to the JIF years among the most extreme self-citing journals across 2013-2015 in both editions.
Finally, to some degree, the element of chance also played a role . As designed, the self-citation analysis flags as candidates for suppression the most extreme outlier population of journals for percentage of JIF citations that are journal self-cites. A number of additional aforementioned quantitative criteria are then considered, which result in some of these candidate journals not being suppressed. For the 2015 analysis there were more candidate journals that did not make the final suppression list when these additional criteria were applied in comparison with the prior two years’ analyses. This chance effect is purely due to the differing characteristics of the datasets.
We remain committed to publishing meaningful metrics that accurately represent a journal’s usage and influence, and journal suppression was adopted as a means of maintaining the integrity of those metrics. We believe that the evident improvements in ethical publication practices stem in part from our strong position on these matters, both in the policies we apply in producing the JCR metrics and as stated in our Journal Selection Process essays. Thomson Reuters also understands that our publishing partners take the matter of deliberate manipulation of citation data as seriously as we do, and we are encouraged by current trends. Whatever actions publishers may have taken to lessen citation anomalies appear to be having an effect. Therefore we view the lower number of 2015 suppressions optimistically, and as a development that moves us closer to the ideal of journal suppression as a concept rather than a practice.
Did you miss any of the posts in our JCR series? Catch up now:
The 2016 Journal Citation Reports Release Is Coming!
Spotlight on: Eigenfactor Metrics
Behind the Scenes of the JCR Selection & Production Processes
Spotlight on: Downloadable Reports in JCR
Spotlight on: visualizations in Journal Citation Reports