The h -index is an author-level metric that measures both the productivity and citation impact of the publications , initially used for an individual scientist or scholar. The h -index correlates with success indicators such as winning the Nobel Prize , being accepted for research fellowships and holding positions at top universities. The index has more recently been applied to the productivity and impact of a scholarly journal [ 2 ] as well as a group of scientists, such as a department or university or country.
Hirsch , a physicist at UC San Diego , as a tool for determining theoretical physicists ' relative quality [ 4 ] and is sometimes called the Hirsch index or Hirsch number. Hirsch intended the h -index to address the main disadvantages of other bibliometric indicators. The total number of papers metric does not account for the quality of scientific publications. The total number of citations metric, on the other hand, can be heavily affected by participation in a single publication of major influence for instance, methodological papers proposing successful new techniques, methods or approximations, which can generate a large number of citations.
The index works best when comparing scholars working in the same field, since citation conventions differ widely among different fields. The h -index is intended to measure simultaneously the quality and quantity of scientific output.
The Kendall's correlation of h -index with scientific awards in physics was found at 34 percent in and zero percent in The h -index is the largest h such that h articles have at least h citations each. For example, if an author has five publications, with 9, 7, 6, 2, and 1 citations ordered from greatest to least , then the author's h -index is 3, because the author has three publications with 3 or more citations.
However, the author does not have four publications with 4 or more citations. Clearly, an author's h -index can only be as great as their number of publications. For example, an author with only one publication can have a maximum h -index of 1 if their publication has 1 or more citations. On the other hand, an author with many publications, each with only 1 citation, would also have an h -index of 1.
