An informetric model for the Hirsch-index

The h-index (or Hirsch-index) was defined by Hirsch in 2005 as the number h such that, for a general group of papers, h papers received at least h citations while the other papers received no more than h citations. This definition is extended here to the general framework of Information Production Processes (IPPs), using a source-item terminology. It is further shown that in each practical situation an IPP always has a unique h-index. In Lotkaian systems h = T-1/alpha, where T is the total number of sources and alpha is the Lotka exponent. The relation between h and the total number of items is highlighted.