Profiling citation impact: A new methodology

A methodology for creating bibliometric impact profiles is described. The advantages of such profiles as a management tool to supplement the reporting power of traditional average impact metrics are discussed. The impact profile for the UK as a whole reveals the extent to which the median and modal UK impact values differ from and are significantly below average impact. Only one-third of UK output for 1995-2004 is above world average impact although the UK's average world-normalised impact is 1.24. Time-categorised impact profiles are used to test hypotheses about changing impact and confirm that the increase in average UK impact is due to real improvement rather than a reduction in low impact outputs. The impact profile methodology has been applied across disciplines as well as years and is shown to work well in all subject categories. It reveals substantial variations in performance between disciplines. The value of calculating the profile median and mode as well as the average impact are demonstrated. Finally, the methodology is applied to a specific data-set to compare the impact profile of the elite Laboratory of Molecular Biology (Cambridge) with the relevant UK average. This demonstrates an application of the methodology by identifying where the institute's exceptional performance is located. The value of impact profiles lies in their role as an interpretive aid for non-specialists, not as a technical transformation of the data for scientometricians.