Revised h index for biomedical research.

Proposed by Hirsch as a quantitative measure of the total output of a researcher, the h index does not work well in the field of life sciences, where an author's position on a paper typically depends on the author's contribution. We revise the h index by weighing first and last authorship papers four times heavier than middle authorship papers. The revised index (r) signifies a shift in how we evaluate the research output in biology and medicine: it places more value on conducting and directing original, independent investigations as compared with contributing to projects conducted and directed by others.