The Hirsch-Index: What Pharmacists Who Publish Should Know

Many pharmacists are active members of the scientific community and often publish their research in peer-reviewed journals. It is likely that pharmacists’ interest in publishing original research will increase as academic pharmacy expands and post-graduate training becomes more ubiquitous.

It is also reasonable to suspect that more pharmacists in academia and industry will be pressured to publish to advance in their respective careers. Often, metrics are used to measure scientific productivity and may be a factor in determining promotions or placement in some institutions. One commonly used metric is known as the Hirsch index, or the h-index. The h-index measures the scientific “impact” or productivity of an individual. An h-index value is calculated based on number of publications and citations an author has to his or her credit.¹For example, if an author has 2 publications that have at least 2 citations each, the h-index is 2, if he or she has 10 papers with at least 10 citations each; the h index is 10, and so on.

The h-index has its advantages, most obvious is that it attempts to measure scientific productivity using both quantitative measures (number of published works) as well as the quality of those works (number of citations). Using citations as the sole measure of scientific productivity means that one individual with a single well-cited paper could appear to be more productive than someone who has produced multiple works over multiple years in various areas of study. Using number of publications as the sole measure of productivity could allow individuals to publish numerous low-quality works and appear to be more productive that someone who is producing fewer higher-quality manuscripts.

The h-index was developed as a more comprehensive way of measuring the scientific productivity of an individual. While convenient, the h-index does have some drawbacks that need to be considered. In my opinion, the most critical problem with the h-index is that there is no consideration for author placement. First and corresponding author status often conveys that those individuals have a much more significant contribution to the publication compared to the other authors. It is not uncommon to have a large study in the biomedical sciences with 10 or more authors, and theoretically, those who contributed a small amount to the study will get the same h-index benefit as those who pioneered and/or managed the study. The h-index can be impacted by inaccurate citation counts, as well as self-citations. The latter allows some individuals to cite themselves excessively to inflate their h-index.²

The h-index attempts to measure scientific productivity, and has been embraced by many. In my opinion, scientific productivity itself is not just regulated to papers and citations. Sharing your work with others via social media, conferences, or other presentations is also valuable. Visibility and dissemination of your work are not as easily quantified as citations and number of publications.

While the h-index is not perfect, it is a popular metric that is being used by many to track scientific productivity. Pharmacists who publish should be aware of the metric and understand its limitations as it may impact career progression.

References

1. Hirsch JE. An index to quantify an individual's scientific research output. Proceedings of the National Academy of Sciences of the United States of America. 2005;102(46):16569-16572.

2. Harzing A-W. Reflections on the h-index. URL: http://www.harzing. com/pop_hindex. htm.