  I introduce a decomposition of the h-index, which is nowadays the leading
criterion to assess the relevance of a scientist in his/her research field.
According to the proposed decomposition, the h-index is the product of two
indicators, the first of which measures the impact of the scientist on the
research community and the second may be seen as a measure of concentration of
the citations in correspondence of a reduced number of papers. The
decomposition is illustrated by an application based on data concerning a group
of top level economists.
