Table 1.
Brief definition of the bibliometric indices considered in the study
| Index | Definition |
|---|---|
| h-index | “A scientist has index h if h of his or her Np papers have at least h citations each and the other (Np—h) papers have fewer than ≤ h citations each” (Hirsch 2005) |
| m-quotient | h/y where h is h index, y is number of years since publishing the first publication |
| g-index | “The g-index g is the largest rank (where papers are arranged in decreasing order of the number of citations they received) such that the first g papers have (together) at least g 2 citations” (Egghe 2006) |
| Individual h-index | Standard h-index divided by the average number of authors in the publications that contribute to the h-index. It aims at reducing the effects of co-authorship. Schreiber’s method was used. It uses fractional paper counts to account for shared authorship of publications, and determines the multi-authored h m index, which is based on the resulting effective rank of the publications using undiluted citation counts |
| Age-weighted citation rate | Number of citations to an entire body of work, adjusted for the age of each individual paper. The number of citations to a given publication is divided by the age of that publication (Publish or Perish implementation) |
| e-index | The (square root) of the surplus of citations in the h-set beyond h 2, i.e., beyond the theoretical minimum required to obtain an h-index of ‘h’. This index aims to differentiate between scientists with similar h-indices, but different citation patterns |
| Contemporary h-index (ac) | h-index weighted by an age-related parametrization (gamma = 4; Delta = 1) to each cited publication, giving less weight to older publications. Citations of a publication published during the current year account for four times. Citations of a publication published 4 years ago account for one time. Citations of a publication published 6 years ago account for 4/6 times, etc |
Notes: All indices, with their corresponding reference, are described on the Publish or Perish Web site: http://www.harzing.com/pophelp/metrics.htm