Hirsch number

The h-index is an index suggested in 2005 by Jorge E. Hirsch of the University of California, San Diego to quantify the scientific productivity of physicists and other scientists based on their publication record.

Definition and Purpose
The index is calculated based on the distribution of citations received by a given researcher's publications. Hirsch writes:
 * A scientist has index h if h of his/her Np papers have at least h citations each, and the other (Np - h) papers have at most h citations each.

In other words, a scholar with an index of h has published h papers with at least h citations each. Thus, the H-index is the result of the balance between the number of publications and the number of citations per publication. The index is designed to improve upon simpler measures such as the total number of citations or publications, to distinguish truly influential scientists from those who simply publish many papers. The index is also not affected by single papers that have many citations. The index works properly only for comparing scientists working in the same field; citation conventions differ widely among different fields.

Online web programs are available to directly calculate a scientist's H-index number. The H-index can also be manually determined using free Internet databases, such as Google Scholar, and serves as an alternative to more traditional journal impact factor metrics, which are not freely available. Because only the most highly cited articles contribute to the h-index, its determination is a relatively simpler process. Hirsch has demonstrated that $$h$$ has high predictive value for whether or not a scientist has won honors like National Academy membership or the Nobel Prize. In physics, a moderately productive scientist should have an $$h$$ equal to the number of years of service while biomedical scientists tend to have higher values.

Criticism
It is not difficult to come up with situations in which $$h$$ may provide misleading information about a scientist's output. Most importantly the fact that $$h$$ is bounded by the total number of publications means that scientists with a short career are at an inherent disadvantage, regardless of the importance of their discoveries. For example, Evariste Galois' h-index is 2, and will remain so forever. Had Albert Einstein died in early 1906, his $$h$$ index would be stuck at 4 or 5, despite his being widely acknowledged as one of the most important physicists, even considering only his publications to that date.

Additionally, some potential drawbacks of the impact factor apply equally to the h-index. For example, review articles are usually more cited than original articles, so a hypothetic author who would only write review articles would have a higher h-index than authors who would actually contribute original research.

Proposals to modify the h-index in order to emphasize different features have been made.

Physicists with high h-indices
Based on the SPIRES HEP Database (Particle and High energy Physics, As of August 2005,): Based on the ISI Web of Science, according to the original paper (all physics):
 * Edward Witten: h = 110 (132 as of December 2005)
 * John Ellis: h = 101
 * Steven Weinberg: h = 88
 * Dimitri Nanopoulos: h = 86
 * Cumrun Vafa: h = 85
 * Nathan Seiberg: h = 84
 * Howard Georgi: h = 77
 * John Schwarz: h = 75
 * Frank Wilczek: h = 68
 * Leonard Susskind: h = 68
 * Mark Wise: h = 67
 * David Gross: h = 66
 * Andrew Strominger: h = 66
 * Roman Jackiw: h = 66
 * Stephen Hawking: h = 62
 * Joseph Polchinski: h = 58
 * Abdus Salam: h = 58
 * Tom Banks: h = 56
 * Sheldon Glashow: h = 53
 * Neil Turok: h = 50
 * Juan Maldacena: h = 49
 * Anthony Zee: h = 49
 * Michael Green: h = 44
 * Michael Peskin: h = 41
 * Gerard 't Hooft: h = 41
 * Alexander Polyakov: h = 38
 * Lisa Randall: h = 38
 * Steve Shenker: h = 36
 * Paul Frampton: h = 35
 * David Politzer: h = 34
 * Lee Smolin: h = 33
 * Brian Greene: h = 32
 * Shamit Kachru: h = 31
 * Eva Silverstein: h = 24
 * Richard Feynman: h = 23
 * Michio Kaku: h = 22
 * Gerald Cleaver: h = 20
 * Paul Dirac: h = 19
 * Alan J. Heeger: (h = 107),
 * Marvin L. Cohen: (h = 94),
 * Arthur C. Gossard: (h = 94),
 * Philip W. Anderson: (h = 91),
 * Steven Weinberg: (h = 88),
 * Michael E. Fisher: (h = 88),
 * Manuel Cardona: (h = 86),
 * Kurt Binder: (h = 81),
 * Pierre-Gilles de Gennes: (h = 79),
 * John N. Bahcall: (h = 77),
 * Zachary Fisk: (h = 75),
 * D.J. Scalapino: (h = 75),
 * Giorgio Parisi: (h = 73),
 * Watt W. Webb: (h = 71),
 * Steven G. Louie: (h = 70),
 * Roman Jackiw: (h = 69),
 * Frank Wilczek: (h = 68),
 * Cumrun Vafa: (h = 66),
 * M. Brian Maple: (h = 66),
 * David J. Gross: (h = 66),
 * Mildred S. Dresselhaus: (h = 62),
 * Stephen W. Hawking: (h = 62).

Based on the ISI Web of Knowledge (all fields):
 * Klaus Ploog: h = 71
 * Arthur Gossard: h = 64
 * Daniel Chemla: h = 61
 * David A. B. Miller: h = 58
 * Ivan K. Schuller: h = 54
 * Marlan Scully: h = 54
 * Carlos Bustamante: h = 51
 * Albert Fert: h = 50
 * David Awschalom: h = 49
 * Alexei Alexeyevich Abrikosov: h = 48
 * Charles T. Rettner: h = 48
 * Stuart Parkin: h = 47
 * Leonid Keldysh: h = 42
 * J.G. Bednorz: h = 40
 * Paul Callaghan: h = 40
 * Ewan Wright: h = 40
 * Constantino Tsallis: h = 38
 * Vladimir Man'ko: h = 36
 * Jacob Bekenstein: h = 34
 * Atac Imamoglu: h = 32
 * Andrew Briggs: h = 30
 * Mikhail Lukin: h = 26

Physical Chemists from Berkeley and Stanford with high h-indices
The following is a list of physical chemists with high h-indices. So far, it has been compiled from "The Everyday Scientist" and ISI Web of Science, using data for only professors at Stanford and U.C. Berkeley:


 * Richard N. Zare: h = 95
 * Gabor A. Somorjai: h = 90
 * Harden M. McConnell: h = 89
 * Graham R. Fleming: h = 75
 * Richard A. Mathies: h = 68
 * John I. Brauman: h = 63
 * A. Paul Alivisatos: h = 62
 * Richard J. Saykally: h = 61
 * Steven G. Boxer: h = 55
 * Michael D. Fayer: h = 52
 * Hans C. Andersen: h = 48
 * Daniel M. Neumark: h = 48
 * W. E. Moerner: h = 45
 * Herbert L. Strauss: h = 43
 * Robert Pecora: h = 41
 * Ronald C. Cohen: h = 33
 * Vijay Pande: h = 31
 * Marcin Majda: h = 28

Biologists with high h-indices
A starting attempt was made at using the physics-oriented h-index for the life sciences (a blanket term for biology, botany, medicine, and so forth). Only ten names were listed in the reference, but if a more solid attempt is made this list will certainly grow. The following list is based on publications from 1983-2002.


 * Solomon H. Snyder: h = 191
 * David Baltimore: h = 160
 * Robert Gallo: h = 154
 * Pierre Chambon: h = 153
 * Bert Vogelstein: h = 151
 * Salvador Moncada: h = 143
 * Charles A. Dinarello: h = 138
 * Tadamitsu Kishimoto: h = 134
 * Ronald M. Evans: h = 127
 * Axel Ullrich: h = 120

Computer scientists with high h-indices
The following are the top 10 computer scientists from this list.


 * 70 Hector Garcia-Molina
 * 65 Scott Shenker
 * 65 Jeffrey D. Ullman
 * 64 Robert Tarjan
 * 60 Don Towsley
 * 59 Takeo Kanade
 * 57 David Culler
 * 57 Deborah Estrin
 * 57 Anil K. Jain
 * 56 Randy H. Katz

Scientists in other fields with high h-indices

 * Endel Tulving: h = 64 (Cognitive psychologist)