Impact factor bias and proposed adjustments for its determination

Area of Science:

• Bibliometrics
• Scientific publishing
• Journal evaluation

Background:

• The impact factor (IF) is a widely used metric for evaluating scientific journals.
• However, the IF has limitations, including biases related to journal self-citation and variations across different scientific fields.
• This study aimed to address these constraints to improve journal evaluation.

Purpose of the Study:

• To evaluate the impact of journal self-citation on the impact factor.
• To assess the influence of scientific field on journal impact factor.
• To investigate methods for improving the accuracy and fairness of the impact factor.

Main Methods:

• Analyzed the top-ranked journals across seven medical fields.
• Calculated corrected impact factors by excluding journal self-citations.
• Normalized impact factors by comparing them to the mean impact factor within each scientific field (IF/fcat).

Main Results:

• A negative correlation was observed between impact factor and both self-cited and self-citing rates.
• Correcting for self-citation did not significantly alter the ranking of the evaluated journals.
• The normalized impact factor (IF/fcat) showed a strong positive correlation with the conventional impact factor.

Conclusions:

• Adjusting the impact factor for self-citation does not substantially change journal rankings.
• Normalizing the impact factor by scientific field (IF/fcat) provides a more comparable metric.
• The IF/fcat metric is positively correlated with the conventional IF, suggesting its validity.