What Is a Good H-Index Required for an Academic Position?
Metrics are important. Even scholars who may not entirely agree with the ways in which academic and scientific impact is currently measured and used cannot deny that metrics play a significant role in determining who receives research grants, employment offers and desirable promotions. The h-index is only one among various kinds of metrics now applied to the research-based writing of professional scholars, but it is an increasingly significant one. Introduced by the physicist Jorge Hirsch in a paper published in 2005, the h-index was designed to assess the quantity and quality of a scientist’s contributions and predict his or her productivity and influence in the coming years. However, its use and importance have quickly expanded beyond physics and the sciences into a wide variety of disciplines and fields of study. If you are applying for a scientific or academic position, hoping for a promotion or in need of research funding, it will therefore be wise to give your h-index score some consideration, but within reason. In some fields, the h-index and other forms of metrics play a very small part if any in hiring and funding, and there are still many other means used by hiring and funding committees to assess scholarly contributions.
The h-index is considered preferable to metrics that measure only a researcher’s number of publications or the number of times those publications have been cited. This is because it combines the two, considering both publications and citations to arrive at a particular value. A scholar who has five publications that have been cited at least five times has an h-index of 5, whereas a scholar with ten publications that have been cited ten times has an h-index of 10. Publication and citation patterns differ markedly across disciplines and fields of study, and the expectations of hiring and funding bodies vary depending on the level and type of position and the kind and size of research project, so it is impossible to say exactly what might be considered an acceptable or competitive h-index in a given situation. H-index scores between 3 and 5 seem common for new assistant professors, scores between 8 and 12 fairly standard for promotion to the position of tenured associate professor, and scores between 15 and 20 about right for becoming a full professor. Be aware, however, that these are gross generalisations and actual figures vary enormously among disciplines and fields: there are, for instance, many full professors, deans and chancellors with very low h-index scores, and an exceptional young researcher with an h-index of 10 or 15 might conceivably still be working on a post doctorate.
As a general rule in many fields, an h-index that matches the number of years a scholar has been working in the field is a respectable score. Hirsch in fact suggested that the h-index be used in conjunction with a scholar’s active research time to arrive at what is known as Hirsch’s individual m. It is calculated by dividing a scientist’s h-index by the number of years that have passed since the first publication, with a score of 1 being very good indeed, 2 being outstanding and 3 truly exceptional. This means that if you have published at least one well-cited document each year since your first publication – a decent textual output by any measure – you are among a successful group of scholars, and if you have published two or three times that number of well-cited documents over the same period of time, you are among the intellectual superstars of your discipline and probably of your time. To put this into perspective, from what I can find online it looks like Stephen Hawking has a score of about 1.6 by this calculation. If you can approach a hiring committee or funding body with anything close to that, you are certainly going to be a serious contender in the competition.
The h-index as a measure of both the quantity and quality of scholarly achievement is considered quite reliable and robust, so it has proved incredibly popular and is now applied not only to individual researchers, but also to research groups and projects, to scholarly journals and publishers, to academic and scientific departments, to entire universities and even to entire countries. As with all metrics, however, the h-index is subject to a number of biases and limitations, so there are significant problems associated with relying solely on h-index scores when making important research and career decisions. The h-index does not, for example, account for publications with citation numbers far above a researcher’s h-index or distinguish any difference between publications with a single author or many. Older publications are counted exactly as more recent ones are and older scholars benefit, whether they have published anything new in years or not. Neither the length of a publication nor the nature of each citation (positive or negative) is considered, so those measures of quantity and quality are not part of the picture. Early career researchers who take the time to delve deeply into an important problem and eventually produce an excellent article and scholars at any stage in their careers who dedicate time to teaching or practical applications of research will have lower scores than those who crank out mediocre articles based on uninteresting research that is nonetheless cited by their colleagues. Finally, the databases from which the h-index and other metrics are determined vary in the types of documents they consider and the fields of study they include, so the same scholar will not receive the same h value across all of them, and accurate comparison across fields and disciplines is impossible.
These and other problems have generated a number of adjustments that are rather similar to Hirsch’s individual m, which, as discussed above, considers a scholar’s active research time in relation to his or her h-index. The g-index gives greater weight to publications whose citation counts exceed a researcher’s h value; the hi index corrects for the number of authors; the hc index corrects for the age of publications, with recent citations earning more counts; and the c-index considers collaboration distance between the author of a publication and the authors citing it. Solutions for comparison between disciplines and fields have included dividing the h-index scores of scholars by the h-index averages in their respective fields to arrive at results that can be compared, but defining fields can be tricky, and larger fields of study with more researchers naturally generate more citations. The databases used for scholarly metrics are constantly upgrading and broadening their inclusiveness to render metrics like the h-index more truly representative of a researcher’s actual productivity and impact, so the accuracy and consistency of these tools are likely to continue improving. However, no new numbers or calculations can add what all of these metrics lack, and that is research content – the valuable and unique content that makes the publication of research a worthy task in the first place.
Committees gathered to hire or promote faculty or to select the recipients of research grants rarely rely solely on metrics when making their decisions. If they are doing their jobs properly, they combine what they can gather from metrics with other information about candidates and their scholarly impact. They do not just notice how many times the papers of candidates have been cited; they read those papers and consider their content, and they pay attention to the other activities of the scholars they are considering. This wider perspective is appropriate for an applicant as well, so if you are polishing your CV, putting together a grant application or preparing for a job interview, look over your own unique achievements with a kindly yet critical eye and consider them in direct relation to what the job posting or grant regulations indicate is wanted. If you happen to have a wonderful h-index score or any other impressive metrics, by all means flaunt them, and if you fear that a low h value will compromise your career aspirations, do what you can to have your publications with lower citation counts read and used more often, update your profiles on the relevant databases, and publish the type of document sure to garner citations in your field, such as a review article.
Do keep in mind, however, that hiring and funding committees are often looking for far more than large numbers of highly cited publications. Admittedly, they rarely balk at them, but universities are also seeking excellent teachers, advisors and administrators, so play up those skills and any related experience you have, and remember that financial supporters of research may be keen to fund scholars who can successfully manage and complete projects, even and perhaps especially if part of the training they offer younger researchers means that their students tend to publish most of the results. Finally, an active online presence in your field established through sharing your research via blogs, professional platforms and social media might not garner the same respect as formal publications, but it can count for a great deal when many universities are working to increase their online activities and funding bodies working to democratise the publication of the research they support. Generally speaking, committees considering applications will be even more likely to google the names of candidates and applicants than to look up the metrics associated with them, so assume that both will be done and ensure that what can be found shares excellent research content and leaves a desirable professional impression of you and your work.