Bollen J, Van de Sompel H, Hagberg A, Chute R, 2009 A Principal Component Analysis of 39 Scientific Impact Measures. PLoS ONE 2009;4(6): e6022.
An interesting analysis on 39 different kinds of indicators to assess scholarly impact in science.
A part from the traditional citation counts, and the common Journal Impact Factor (that should be used cautiously), new methods like log usage data and social network analysis are reported. However, in the opinion of the authors, it is important to stress that we do not have a universally accepted, golden standard of impact to calibrate any new measures to. It is even difficult to define "scientific impact” precisely. And it may be understood and measured in many different ways. The issue thus becomes which impact measures best express its various aspects and interpretations. In conclusion, scientific impact is a multi-dimensional construct that can not be adequately measured by any single indicator, although some measures are more suitable than others.