  Utilizing the Hirsch index h and some of its variants for an exploratory
factor analysis we discuss whether one of the most important Hirsch-type
indices, namely the g-index comprises information about not only the size of
the productive core but also the impact of the papers in the core. We also
study the effect of logarithmic and square-root transformation of the data
utilized in the factor analysis. To demonstrate our approach we use a real data
example analysing the citation records of 26 physicists compiled from the Web
of Science.
