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 fieldnormalized indicators can be evaluated, and we consider the sensitivity of scientometric analyses to the choice of a field normalization approach.