Citation Metrics: A Primer on How (Not) to Normalize.
Citation metrics are increasingly used to appraise published research. One challenge is whether and how to normalize these metrics to account for differences across scientific fields, age (year of publication), type of document, database coverage, and other factors. We discuss the pros and cons for normalizations using different approaches. Additional challenges emerge when citation metrics need to be combined across multiple papers to appraise the corpus of scientists, institutions, journals, or countries, as well as when trying to attribute credit in multiauthored papers. Different citation metrics may offer complementary insights, but one should carefully consider the assumptions that underlie their calculation.
Meta-Research Innovation Center at Stanford (METRICS), Stanford University, Stanford, California, United States of America.|Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America.|Department of Health Research and Policy, Stanford University School of Medicine, Stanford, California, United States of America.|Department of Statistics, Stanford University School of Humanities and Sciences, Stanford, California, United States of America.
John P A
JP
Ioannidis
SciTech Strategies, Inc., Albuquerque, New Mexico, United States of America.
Kevin
K
Boyack
Centre for Science and Technology Studies, Leiden University, Leiden, Netherlands.
Paul F
PF
Wouters
D015706:Bibliometrics; D035843:Biomedical Research; D003627:Data Interpretation, Statistical; D016208:Databases, Factual; D006801:Humans