Spearman, CM; Quigley, MJ; Quigley, MR; Wilberger, JE. 2010. Survey of the h index for all of academic neurosurgery: another power-law phenomenon?. JOURNAL OF NEUROSURGERY 113 (5): 929-933

[Eugene Garfield]

Spearman, CM; Quigley, MJ; Quigley, MR; Wilberger, JE. 2010. Survey of the h 
index for all of academic neurosurgery: another power-law phenomenon?. 
JOURNAL OF NEUROSURGERY 113 (5): 929-933..

Author Full Name(s): Spearman, Christopher M.; Quigley, Madeline J.; Quigley, 
Matthew R.; Wilberger, Jack E.

Language: English
Document Type: Article
Author Keywords: h index; bibliometrics; power law; academic neurosurgery
KeyWords Plus: IMPACT FACTOR; DISTRIBUTIONS; RANK; UNIVERSALITY

Abstract: Object. The h index is a recently developed bibliometric that 
assesses an investigator's scientific impact with a single number. It has rapidly 
gained popularity in the physical and, more recently, medical sciences.
Methods. The h index for all 1120 academic neurosurgeons working at all 
Electronic Residency Application Service listed training programs was 
determined by reference to Google Scholar. A random subset of 100 individuals 
was investigated in PubMed to determine the total number of publications 
produced.
Results. The median h index was 9 (range 0-68), with the 75th, 90th, and 95th 
percentiles being 17, 26, and 36, respectively. The h indices increased 
significantly with increasing academic rank, with the median for instructors, 
assistant professors, associate professors, and professors being 2, 5, 10, and 
19, respectively (p < 0.0001, Kruskal-Wallis; all groups significantly different 
from each other except the difference between instructor and assistant 
professor [Conover]). Departmental chairs had a median h index of 22 (range 3-
55) and program directors a median of 17 (range 0-62). Plot of the log of the 
rank versus h index demonstrated a remarkable linear pattern (R-2 = 0.995, p < 
0.0001), suggesting that this is a power-law relationship.
Conclusions. A survey of the h index for all of academic neurosurgery is 
presented. Results can be used for benchmark purposes. The distribution of the 
h index within an academic population is described for the first time and 
appears related to the ubiquitous power-law distribution. (DOI: 
10.3171/2010.4.JNS091842)

Addresses: [Spearman, Christopher M.; Quigley, Madeline J.; Quigley, Matthew 
R.; Wilberger, Jack E.] Allegheny Gen Hosp, Dept Neurosurg, Pittsburgh, PA 
15212 USA

Reprint Address: Quigley, MR, Allegheny Gen Hosp, Dept Neurosurg, 420 E N 
Ave,Suite 302, Pittsburgh, PA 15212 USA.

E-mail Address: q at mattquigley.com
ISSN: 0022-3085
DOI: 10.3171/2010.4.JNS091842
URL: http://thejns.org/doi/abs/10.3171/2010.4.JNS091842