Size matters! Association between journal size and longitudinal variability of the Journal Impact Factor

PLoS ONE, 2019 · DOI: https://doi.org/10.1371/journal.pone.0225360 · Published: November 22, 2019

Simple Explanation

The study investigates the relationship between the size of a journal (number of articles published) and how much its Journal Impact Factor (JIF) changes over time. The findings show that larger journals tend to have more stable JIFs, meaning their impact factors don't fluctuate as much from year to year compared to smaller journals. However, this relationship can change for journals with a very high number of total citations, suggesting that both size and overall citation volume play a role in JIF variability.

Study Duration

12 years (2005-2017 JCR years)

Participants

n = 4792 journals with complete JIF data, n = 8750 journals total

Evidence Level

Not specified

Key Findings

1
Larger journals generally exhibit smaller annual changes in their Journal Impact Factor (JIF) compared to smaller journals, indicating greater stability.
2
The negative association between journal size and JIF variability can be reversed for journals with a very large number of total citations.
3
The study provides a regression model that can be used to predict JIF variability based on journal size and total citations.

Research Summary

This study analyzes the relationship between journal size and the longitudinal variability of the Journal Impact Factor (JIF) using a comprehensive dataset of journals from the Incite Journal Citation Reports (JCR). The findings reveal that larger journals generally experience smaller annual changes in their JIF compared to smaller journals, suggesting that journal size is a predictor of JIF stability. The authors conclude that journal size should be considered when evaluating changes in a journal's JIF, as smaller journals may exhibit greater fluctuations due to smaller sample sizes.

Practical Implications

Library Journal Subscriptions

Librarians should consider journal size when making decisions about journal subscriptions, as JIF changes in smaller journals may be less reliable indicators of overall journal quality.

Manuscript Submissions

Authors influenced by JIF changes when selecting a target journal should consider the longitudinal stability of the JIF, using journal size as a surrogate parameter for JIF variability.

JIF Evaluation

Decision-makers should exercise caution when interpreting JIF changes, particularly for smaller journals, recognizing that these changes may be due to statistical fluctuations rather than substantive shifts in journal performance.

Study Limitations

1
The study relies on the Journal Impact Factor (JIF), which is subject to various criticisms regarding its calculation and use.
2
The analysis is based on data from the JCR database, which has subscription-based access restrictions.
3
The study acknowledges that other criteria besides JIF influence journal subscription decisions at academic libraries.

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