Measuring an individual researcher's impact: new directions and challenges.

Metrics which quantify the impact of a scientist are increasingly incorporated into decisions about how to rate and fund individuals and institutions. Several commonly used metrics, based on journal impact factors and citation counts, have been criticised as they do not reliably predict real-world impact, are highly variable between fields and are vulnerable to gaming. Bibliometrics have been incorporated into systems of research assessment but these may create flawed incentives, failing to reward research that is validated, reproducible and with wider impacts. A recent proposal for a new standardised citation metric based on a composite indicator of 6 measures has led to an online database of 100 000 of the most highly cited scientists in all fields. In this perspective article, we provide an overview and evaluation of this new citation metric as it applies to mental health research. We provide a summary of its findings for psychiatry and psychology, including clustering in certain countries and institutions, and outline some implications for mental health research. We discuss strengths and limitations of this new metric, and how further refinements could align impact metrics more closely with wider goals of scientific research.