A meta-analysis of impact factors of astrophysics journals
Rayani Venkat Sai Rithvik, Shantanu Desai
TL;DR
This study re-evaluates journal impact factors for 38 astrophysics journals by computing ADS-based metrics and comparing them with Clarivate's official factors, highlighting where ADS and official counts diverge due to cross-disciplinary content. It introduces a New Impact Factor based on the median of yearly citations to papers published in the previous two years and analyzes its behavior alongside the Old Factor. The results show broad agreement between ADS and official factors for most journals, with notable exceptions such as Nature, and reveal large fractional differences between the New and Old factors for a couple of titles due to citation outliers. The work provides open-source code for reproducing the analysis and discusses the limitations of impact factors, proposing future work on extending the analysis to five-year factors.
Abstract
We calculate the 2024 impact factors for the 38 most widely used journals in Astrophysics, using the citations collated by NASA/ADS (Astrophysics Data System) and compare them to the official impact factors. This includes journals which publish papers outside of astrophysics such as PRD, EPJC, Nature, etc. We also propose a new metric to gauge the impact factor based on the median number of citations in a journal and calculate the same for all the journals. We find that the ADS-based impact factors are mostly in agreement, albeit higher than the official impact factors for most journals. The journals with the maximum fractional difference in median-based and old impact factors are JHEAP and PTEP. We find the maximum difference between the ADS and official impact factor for Nature.