The journal Φ index and highly cited papers

The journal Φ index is a standardized scale-independent citation indicator. Since it is free from the scale dependence that plagues citation averages due to the skewness of citation distributions, it has been proposed [1] as a fairer indicator than the Journal Impact Factor for journal comparisons. But how well does the Φ index capture a journal's citation footprint with regard to highly cited papers? This question matters for research assessment, because of the increased difficulty for transformative, groundbreaking papers—many of which become highly cited eventually—to appear in high Impact Factor journals. To answer this question we analyze papers that were cited at the 99^th percentile in their academic field per publication year, and were designated as "highly cited papers" by Clarivate Analytics' Essential Science Indicators. We compare journal rankings based on the number of highly cited papers, with Φ index and Impact Factor rankings. We find that Φ index rankings have a considerably higher similarity with rankings of highly cited papers. Thus, apart from removing the scale dependence of Impact Factor rankings, the Φ index is also a better descriptor of a journal's potential at the high end—in capturing highly cited papers.

[1] M. Antonoyiannakis, Quantitative Science Studies 1, 639 (2020).