Reforming research in the NHS

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

6 December 2005

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.

Jayant S Vaidya, Senior Lecturer/ Consultant Surgeon

University of Dundee, Ninewells Hospital and Medical School, DD1 9SY

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