Towards a new crown indicator: An empirical analysis

TL;DR

This paper empirically compares two normalization methods for citation-based research performance indicators, highlighting their similarities at large scales and differences at smaller levels, with attention to recent publications.

Contribution

It provides an empirical evaluation of two normalization mechanisms for citation indicators, informing the adoption of a new crown indicator.

Findings

Differences between mechanisms are minimal at high aggregation levels.

At lower aggregation levels, differences are more noticeable.

Recent publications require special handling due to low citation counts.

Abstract

We present an empirical comparison between two normalization mechanisms for citation-based indicators of research performance. These mechanisms aim to normalize citation counts for the field and the year in which a publication was published. One mechanism is applied in the current so-called crown indicator of our institute. The other mechanism is applied in the new crown indicator that our institute is planning to adopt. We find that at high aggregation levels, such as at the level of large research institutions or at the level of countries, the differences between the two mechanisms are very small. At lower aggregation levels, such as at the level of research groups or at the level of journals, the differences between the two mechanisms are somewhat larger. We pay special attention to the way in which recent publications are handled. These publications typically have very low citation counts and should therefore be handled with special care.