Field normalization of scientometric indicators

When scientometric indicators are used to compare research units active in different scientific fields, there often is a need to make corrections for differences between fields, for instance differences in publication, collaboration, and citation practices. Field-normalized indicators aim to make such corrections. The design of these indicators is a significant challenge. We discuss the main issues in the design of field-normalized indicators, and we present an overview of different approaches that have been developed for dealing with the problem of field normalization. We also discuss how field-normalized indicators can be evaluated, and we consider the sensitivity of scientometric analyses to the choice of a field normalization approach.