Reflections on norms for the h-index and related indices

Prof. Anne-Wil Harzing, University of Melbourne
Web: www.harzing.com
Email: pop@harzing.com

Document link: http://www.harzing.com/pop_norm.htm

Third version, 7 January 2008

Introduction

Ever since Publish or Perish has been available, academics have asked me for "norm scores" for the various indices. I guess everyone likes to compare himself or herself to see how they are doing. I have always hesitated to do this as these scores are so easily taken out of context and can take on a life of their own.

However, currently the only publications discussing the h-index and related indices deal with academics in the (Natural) Sciences. There are large differences in research output between the different disciplines (see Reflections on the h-index). H-indices in the Natural Sciences are much higher than in the Social Sciences and Humanities. Hence, I felt that in order to support academics in the Social Sciences and Humanities it would be appropriate to provide some systematic evidence that lower citation indices can be expected in these disciplines. A calculation of citation metrics for an individual academic requires one to be at least familiar with the field in question (in order to be able to eliminate publications by authors with similar names) and preferably with the individual’s work. Therefore, my "norm scores" only pertain to the two fields that I am familiar with: Management and International Business.

Method

It is difficult to establish an appropriate comparison group. However, I think most academics will agree that fellow academics who have been elected as presidents of the peak professional organization in their field would probably constitute an appropriate (if ambitious) benchmark. Therefore, I have calculated the various citation metrics (h-index, g-index, contemporary h-index and individual h-index) for presidents of the Academy of Management (AoM) and the Academy of International Business (AIB) for roughly the last 20 years. Since AIB presidentship only rotates every 2 years, the data are based on 11 individuals, whereas for AoM they are based on 20 individuals.

It is important to note that the record of specific individuals might be both underestimated and overestimated. Most of the publications of academics that were presidents in the early years will be relatively old. Google Scholar does not perform as well for older publications, because these publications and the publications that cite them have not (yet) been posted on the web. Hence their citation metrics might be understated. On the other hand, given that Google Scholar cannot go back in time, we calculated their citation metrics as of the current date, rather than the date at which they became president, hence overstating their citation metrics. For the Academy of Management presidents I calculated the average scores for the 1988-1997 and 1998-2007 periods separately and did not find a significant difference.

However, since most presidents of AIB and AoM are senior, well-established scholars they will have published a lot of their important work a while ago. This first of all means that their contemporary h-indices might be lower than those of newly-minted professors. It also means that Google Scholar might not pick up all the citations to their work as it does not perform as well for older publications. On the other hand, the overall top scorer in the combined group of AIB and AoM presidents (John Dunning) is one of the oldest academics in the group and has a high contemporary h-index.

Results

With the aid of Publish or Perish I found the following citation metrics as of 6 March 2007:

As of 6 March 2007	h-index	g-index	h_c	h_I,norm
Academy of Management Presidents	20	43	11	15
Academy of International Business Presidents	15	31	9	13

Other norm scores

I invite academics to submit norm scores for similar groups in their own subdiscipline with a short description of their search parameters. I would suggest that comparison groups need to include at least 10 academics (and preferably more) to avoid idiosyncrasies. If I am confident that the data are accurate, I will post them on my website with attribution to the person who has compiled them. Please submit your results to pop@harzing.com.

Research Performance of Senior Level Marketing Academics in the Australian Universities: An Exploratory Study Based on Citation Analysis, a paper by Mohammed A. Razzaque and Ian F. Wilkinson, presented at the Australia New Zealand Marketing Academy Conference (ANZMAC), University of Otago, New Zealand, Dec 1-3 2007.
Citation Benchmarks for Articles Published by Australian Marketing Academics, a paper by Geoff Soutar, In M. Thyne, K. R. Deans and J. Gnoth (eds.), Conference Proceedings of the 2007 ANZMAC Conference. Dunedin: Department of Marketing, University of Otago, 3515-3520.