The Integrated Impact Indicator (I3) Revisited: A Non-Parametric Alternative to the Journal Impact Factor

TL;DR

The paper introduces I3*, a non-parametric, size-dependent journal impact indicator that correlates with citations and publications, offering a robust alternative to traditional impact metrics like JIF and h-index.

Contribution

It proposes the I3* metric with percentile-based weighting as a novel, statistically testable, non-parametric impact indicator applicable to over 10,000 journals.

Findings

I3* correlates with citation and publication counts.

I3*/N provides a size-independent impact measure.

I3* aligns with two- and five-year Journal Impact Factors.

Abstract

We propose the I3* indicator as a non-parametric alternative to the Journal Impact Factor (JIF) and h-index. We apply I3* to more than 10,000 journals. The results can be compared with other journal metrics. I3* is a promising variant within the general scheme of non-parametric indicators I3 introduced previously: it provides a single metric which correlates with both impact in terms of citations (c) and output in terms of publications (p). We argue for weighting using four percentile classes: the top-1% and top-10% as excellence indicators; the top-50% and bottom-50% as output indicators. Like the h-index, which also incorporates both c and p, I3*-values are size-dependent; however, division of I3* by the number of publications (I3*/N) provides a size-independent indicator which correlates strongly with the two- and five-year Journal Impact Factors (JIF2 and JIF5). Unlike the h-index, I3* correlates significantly with both the total number of citations and publications. The values of I3* and I3*/N can be statistically tested against the expectation or against one another using chi-square tests or effect sizes. A template (in Excel) is provided online for relevant tests.