Normalizing Citations – Beyond the H-index

The proper metric for an academic’s influence on the academic world of academic publishing is academic citations. An academic might make many (say 100) small contributions, each cited a small number (say 10) of times, or one contribution cited widely (say 1000) times. Neither is inherently superior, despite claims to the contrary, a

Citation needed. Source: Unknown.
Citation needed. Source: Unknown.

nd for the academic in question, it was probably easier to write one widely cited piece than 100 smaller ones, but that was unpredictable at the time.

Academic citations are cumulative distribution function, they can never go down (they can with retractions, but we will neglect that). So by this measure on average senior academics appear more influential than younger academics, which they of course are. But this is not a useful measure for filtering prospective candidates for hiring and promotion, which is why these metrics exist, to sort people based on productivity and establish a social hierarchy.

So to begin, we have two corrections to make. First, senior academics have more opportunities to write papers. A junior academic simply has not had the cumulative time to author 100 papers. Second, the senior academic’s papers have had more time to accumulate citations. So I suggest dividing total citations by Years^2 to account for these two temporal accumulating factors.

But which “Years”? Years since terminal degree? — This favors the young who start publishing before their degree. Years since they began their degree? Almost no one has any paper in year 1 of their graduate career. So we can estimate and split the difference and say years since graduation with terminal degree +2, on the theory that by the time you graduate you should have had at least 3 papers, and that means you started about 2 years before graduation. Still this is highly sensitive to assumptions for younger academics, it will wash out for the older academics. Domains will vary of course in terms of publishing culture.

There are other problems, for instance, co-authorship. At the extreme, all 108 billion people who ever lived have contributed fractionally to every paper, but they don’t all get co-authorship (except on experimental physics papers). But someone who puts all of their PhDs on all of their group’s papers is gaming the system to the detriment of those who assign more individually authored papers. So each citation should be divided by the fraction of authorship that the academic in question deserves. While this is impossible to assess, (promotion files sometimes ask for percentages on co-authored papers, but this is never systematically estimated or consistent). Computing an average dividing by the number of authors on the paper is a good surrogate.

I am not in this business of bibliometrics, I will leave that to others. But hopefully someone in the industry (Scopus, Web of Science, Google Scholar) can run the proposed corrections on these databases and produce a normalized citation measure as a standard output.

Planning for Place and Plexus: Metropolitan Land Use and Transport

Planning for Place and Plexus: Metropolitan Land Use and Transport by David Levinson and Kevin Krizek is now out and available for pre-order. I received my copies today and am quite pleased with how it came out.
Growing out of a course we taught on transportation and land use (PA8202/CE8202: Networks and Places), the book took many years, and I need to think my co-author Kevin Krizek, the publisher Routledge, and their staff and contractors, notably Katy Low, Ben Woolhead, Andrew Craddock, Victoria Johnson, Eleanor Rivers, Jane Wilde, Kate McDevitt, David McBride, our artist Doug Benson, and CTS’s Peter Park Nelson for making this real. My mailbox storing correspondence I have received on the book (excluding what I sent) numbers 723 messages since July 2002. I don’t even want to think about how difficult this must have been without email.
The blurb on the book brochure says:
Planning for Place and Plexus provides a fresh and unique perspective
on metropolitan land use and transport networks, challenging current
planning strategies and offering frameworks to understand and evalu-
ate policy.
The book suggests actions for the future urban growth of metropolitan
areas and includes current and cutting edge theory, findings, and rec-
ommendations which are cleverly illustrated throughout using interna-
tional examples. It is a valuable resource for students, researchers,
practitioners, and policy advisors working across transport, land use,
and planning.
‘A lively, engaging book…which uses neoclassical economic principles…in a
digestible format. The authors go so far as to draw from the film “Thelma and
Louise” to show how game theory can be applied in predicting whether some-
one will drive or take public transit. This provocative, highly relevant book de-
serves to be on the bookshelf of everyone concerned with urban planning and
transportation.’
— Robert Cervero, Professor and Chair, Department of City and Regional Planning, University of California, Berkeley