Relative Specialization / Activity Index

The Relative Specialization Index and the closely related Activity Index measure how much a country, institution, or other unit concentrates its research effort in a given field relative to a global benchmark. The Activity Index, popularized by J. Davidson Frame in the 1970s, compares a unit's share of its own output devoted to a field against the world's share of output in that field: a value above 1 means the unit is more active (more specialized) in that field than the world average, and below 1 means less. András Schubert and Tibor Braun's relative-indicator framework formalized this family and introduced bounded, symmetric variants and 'relational charts' that pair publication activity with citation 'attractivity'. These indices are the scientometric analogue of revealed comparative advantage in trade and are central to national and institutional research-profiling.