Criticism on the hg-index

Although composition of bibliometric indicators appears to be desirable, in many cases it may be misleading. After a brief introduction on the properties of scales of measurement, the attention of this communication is focused on a recent composite indicator, the hg-index, suggested by Alonso et al. (Scientometrics 82(2):391-400, 2010). Specifically, hg-index has three major criticalities: (1) the hg scale is the result of a composition of the h- and g-indices, which are defined both on ordinal scales, (2) the equivalence classes of hg are questionable and the substitution rate between h and g may arbitrarily change depending on the specific h and g values, (3) the apparent increase in granularity of hg, with respect to h and g, is illusory and misleading. Argument is supported by several examples.