In today’s world, we rank everything, from college basketball teams to cookies that go well with milk. A simple way of quantifying quality eases us through the maze of decisions in our daily life. But, certain areas prove to be quite difficult to rank simply. One such category is the influence a researcher has in the giant information network of academia. We all know of the few elite awards, such as the Nobel Prize and the Fields Medal, that recognize academic achievement, but can we easily quantify the influence all researchers have in the information network?

In 2005, J.E. Hirsch of the University of California at San Diego developed a system to measure the scientific output of a researcher. 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 no more than h citations each.” Basically, Hirsch has developed a one-number index to quantify the power and influence an academic has had in the information network of scientific citations. That index is the number of papers a scientist has with that many citations each.

Hirsch claims that his system has advantages over many other potential systems. For example, one way to quantify would be with the total number of papers produced, but that disregards whether or not those papers are actually being read. Another way would be to rank by total citations, but that allows for one outstanding paper, maybe coauthored, to catapult a researcher very high in the rankings. Or maybe the ranking could be based on number of citations per paper, but that would reward low productivity, according to Hirsch. Other, more complicated systems, like providing a minimum threshold of citations for a paper to count, eliminate these disadvantages, but are more clunky that the simple and elegant h-index.

Hirsch has found a way to analyze the links (citations) between the nodes (papers) in the information network of scientific research to quantify power and influence in the network through a one-number index. Similar to the hub/authority update procedure, the Hirsch index uses only links to determine strength in the network. The Hirsch index provides an interesting and simple way to find the most powerful nodes in the information network of science.

Here is a link to the original article:

“An index to quantify an individual’s scientific research output”

J.E. Hirsch

http://arxiv.org/abs/physics/0508025