16.3.5 Hirsch's m and individual m

Proposed by J.E. Hirsch in his paper An index to quantify an individual's scientific research output, arXiv:physics/0508025 v5 29 Sep 2005. It is calculated by dividing the h-index by the number of years the academic has been active. The latter is defined as the number of years that have passed since publication of the first paper. The Individual m is calculated by dividing the individual h-index by the number of years the academic has been active.

In his article Hirsch proposes norm scores for m for Physicists. He suggests that academics with an m of 1 can be considered to be successful academics, whilst academics with an m of 2 or 3 can be considered respectively as outstanding or truly unique individuals. To put this into context, consider that a popular physicist such as Stephen Hawking has an m of “only” 1.59. I would therefore suggest that we should consider an m of around 1 to reflect excellence rather than simple success in terms of research impact.

As can be seen in Table 2 and Figure 12, on average academics in both general fields have a very similar Hirsch's m index, with 0.95 for the Sciences and 0.93 for the Social Sciences and Humanities. This suggests that on average professors at the University of Melbourne should be considered to display excellence in terms of research impact.

Figure 12: Hirsch's m and Individual m for academics in different disciplines

Figure 12

In fact, most of the individual academics hover around the m=1.0 mark, with only the Mathematician and the Cinema Studies academics scoring substantially lower and the Business academic scoring substantially higher. The latter case might be slightly anomalous as this academic has only been active for 16 years. She might not be able to maintain this level of performance over the next decades.

Looking at the individual m-index, which corrects for the number of co-authorships we see that on average academics in the Social Sciences and Humanities perform better than academics in the Sciences as their individual m-index is only 20% lower than their m-index, whilst academics in the Sciences experience nearly a 40% drop.