Scientific Community Debates Standard Definition of "Impact Factor"

Paris, France

The General Conference on Weights and Measures reconvened this week in an emergency session aimed at reaching a consensus over the definition of impact factor (IF).  Impact factor has long been the unit of measure generally regarded as appropriate for quantifying the scientific importance of a particular publication.

Empirical determination of impact factor has long been a laborious task and dates back to 1975 when print journals were pyrolyzed and the effluent hot gas run through a flame ionization detector.  Advances in furnace design, coupled with digital detectors in the mid-1990's allowed impact factor to be quantified to much higher degrees of precision.  The rise of computational chemistry in the early 2000's allowed unrestricted Hartree-Fock calculations to be applied to predictive models of impact factor determination.

Despite the numerous advances in determining IF, state-of-the-art methods still only allow quantification to four decimal places of precision.  This shortfall results in the contribution of "nanoimpact" journals -- those emitting infinitesimally low IF -- being neglected entirely.

The current standard impact factor model used by scientists relies on the International Impact Factor Prototype (IIFP), a physical copy of the latest issue of the New England Journal of Medicine, stored in a climate controlled vault under armed guard -- defined as precisely 55.87(3) IF.  Other definitions of impact factor exist; however, most rely on relationships between non-SI derived quantities, such as the difficult to interpret H-index.  Moreover, the discrepancy between competing definitions introduces error larger in magnitude than the IF of some publications.

Still, many conference participants remain skeptical that the time is right to unify and standardize the definition of impact factor.  "There's some interesting work coming out of Oak Ridge National Lab which seems to imply that impact factor may, in fact, be quantized," stated Thomas Schwartz, PhD.  "That would be a game changer.  Ultimately, in my opinion there's simply not enough data to develop an authoritative unified model," added Schwartz.

Meanwhile, scientists at CERN remain hopeful that forthcoming high-energy experiments involving five of the six particle accelerators in operation will elucidate a standard definition of the IF.  "We will accelerate two high impact print journals to relativistic speeds -- 7.6% of the speed of light -- and collide them in our Compact Linear Collider facility.  The resulting fragments of subatomic particles will be quantified by our suite of over 15,000 independent detectors.  It is our hope to detect the theorized impactron, the elementary particle responsible for giving matter impact factor," explained Fabiola Gianotti, director general of CERN.