Letters

Reforming research in the NHS

BMJ 2005; 331 doi: http://dx.doi.org/10.1136/bmj.331.7528.1339-c (Published 01 December 2005) Cite this as: BMJ 2005;331:1339

V-index: A fairer index to quantify an individual 's research output capacity

The m value [1] compensates for the academic age of the researcher
such that       h ~ m . n 
(where n is the academic age). An m value of 1 (20 papers cited at least
20 times over a 20 year career) indicates a successful researcher, 2 (40 papers
cited at least 40 times over a 20 year career)– outstanding and 3 a truly
unique individual [1].

However, even the m value assumes that the researcher is working
full time. This may not be the case in some fields. For example, clinical
academics typically devote 40% to 50% of their time to research. So I propose a
v-index such that h ~ v . n /p where p is the proportion of time devoted to
research.

The table 1 uses data from science citation index and uses typical
values of p for scientists and clinical academics. These individuals have had
major impact on their field and the table shows how the v-index may be a better
than m value as a fair comparator.

Yours sincerely

Jayant
S Vaidya1

1Department of Surgery and Molecular Oncology,
University of Dundee, Level 6, Ninewells Hospital and Medical School, Dundee
DD1 9SY, UK

References

1.         Hirsch J.E. An
index to quantify an individual’s scientific research output
arXiv:physics/0508025 v5 29 Sep (2005)

2.         Ball P. Index
aims for fair ranking of scientists Nature
436, 900  (2005)

 

Table 1 : h-index, m value and v-index for 4 individuals.

Name

h-index

Academic age (n)

m value

= h / n

Proportion of time devoted to
research (p)

v-index

= h / n /p

SirPaul Nurse
(Scientist and Nobel Laureate)

86

30

2.7

0.95

2.8

Sir David Lane
(Scientist)

83

32

2.8

0.95

2.9

SirAlfred Cuschieri
(Academic Surgeon)

45

30

1.5

0.45

3.3

ProfMichael Baum
(Academic Surgeon)

40

29

1.4

0.45

3.1

 

 

Competing interests:
None declared

Competing interests: The newly described h-index[1,2] attempts to standardise assessmentof the breadth of impact of a researcher on his/her field. The h-index is thenumber of publications by a researcher that are cited at least as many times.For example if 40 publications are cited at least 40 times, the h-index is 40.

06 December 2005
Jayant S Vaidya
Senior Lecturer/ Consultant Surgeon
University of Dundee, Ninewells Hospital and Medical School, DD1 9SY
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