Reasons for Journal Impact Factor Changes: Influence of Changing Source Items.

Area of Science:

• Bibliometrics
• Scholarly Communication
• Journal Evaluation

Background:

• The journal Impact Factor (IF) is a widely used metric for evaluating journal influence.
• Concerns exist regarding the manipulation and validity of IF calculations.
• Previous analyses have not systematically examined the drivers of significant IF fluctuations.

Purpose of the Study:

• To systematically analyze the causes of significant journal Impact Factor changes.
• To classify IF variations as 'valid' or 'invalid' based on their contribution to measuring journal quality.
• To investigate the role of numerator (citations) and denominator (articles) in IF fluctuations.

Main Methods:

• Analysis of a cohort of JCR-listed journals with substantial absolute IF changes (ΔIF ≥ 3.0) between 2013-2014.
• Examination of the relative contributions of changes in article count and citation count to IF variations over five years.
• Development of a classification system for 'valid' and 'invalid' IF change scenarios.

Main Results:

• A significant portion (18%) of observed IF increases were classified as 'invalid'.
• 'Invalid' IF increases were primarily driven by a decrease in the number of published articles (denominator).
• This suggests that IF can be artificially inflated by reducing publication output.

Conclusions:

• Reductions in publication output can lead to misleading increases in journal Impact Factor.
• The current IF metric may not accurately reflect true journal quality when the denominator is manipulated.
• Implementing control mechanisms for article count variations could enhance the expressiveness of the IF metric.