Q. What is an h-index value?

The h-index is a number meant to represent the productivity and the impact of a researcher or group of researches in their field.  This particular bibliometric tool was proposed by and is named after physicist Jorge Hirsch.

The h-index is calculated by counting the number of publications for which the author has been cited by other authors at least that same number of times.  For instance, an h-index of 14 means that the scientist has published at least 14 papers that have each been cited at least 14 times.  If the scientist's 15th most cited publication was cited only 7 times, the h-index would remain at 14.  If the scientist's 15th most cited publication was cited 15 or more times, the h-index would increase to 15.

Part of the purpose of the h-index is to give a picture of the author's impact over time, eliminate the outlier effect of a few publications that might give a skewed picture.  For example, if an author published one paper several years ago that was cited 5,243 times, but has since only published papers that have been cited only a few times each, a simple citation count for that author could make it seem that their work was extremely significant in the field.  The h-index, however, would be much lower, signifying that the author's entire body of work was not necessarily as significant.

It should be noted that different sources (i.e. Scopus, Web of Science, Google Scholar, etc.) will give different values for the same person's h-index.  This is because each database calculates the h-index value based on the citations it contains.  Since different databases cover different journals over different ranges of years, the h-index result therefore varies.  In addition, a value that is considered a "good" h-index may change depending on the area of research.  A number that is considered low in one field might be considered quite high in another field.

For additional information on bibliometrics, see our LibGuide titled "Tracking Your Publications" here.

[NOTE:  This answer borrows extensively from that posted on the MD Anderson Cancer Center's Research Medical Library website here. This information is used with permission.]