Age-specific citation rates and the Egghe-Rao function
Burrell (Scientometrics, 55 (2003) in press) has pointed out certain similarities between retrospective citation age studies and reliability theory. Here we extend these connections by considering the so-called failure rate function from reliability which is re-interpreted as the age-specific citation rate (ASCR). This is linked to earlier studies of retrospective citation distributions by Egghe and Ravichandra Rao (Information Processing and Management 28 (1992) 201) who introduced a function claimed to correspond to what they termed the (discrete time) obsolescence or ageing function. Further analysis reveals that their function is essentially one whose behaviour reflects that of the ASCR. (C) 2002 Elsevier Ltd. All rights reserved.
age-specific citation rate egghe-rao function failure rate retrospective citation age distributions graphical methods