方法对比

	Crown Indicator (CPP/FCSm)	e-Index (Excess Citations)
领域	文献计量学	文献计量学
方法族	Process / pipeline	Process / pipeline
起源年份	1995	2009
提出者	Henk F. Moed, R. E. De Bruin & Th. N. Van Leeuwen (CWTS Leiden)	Chun-Ting Zhang
类型	Field-normalized citation impact indicator (ratio of averages)	Author-level excess-citation impact index
开创性文献	Moed, H. F., De Bruin, R. E., & Van Leeuwen, T. N. (1995). New bibliometric tools for the assessment of national research performance: Database description, overview of indicators and first applications. Scientometrics, 33(3), 381-422.	Zhang, C.-T. (2009). The e-index, complementing the h-index for excess citations. PLoS ONE, 4(5), e5429.
别名	CPP/FCSm, old crown indicator, Leiden crown indicator, CWTS crown indicator	Zhang e-index, excess citation index, e index
相关	3	3
摘要	The crown indicator, written CPP/FCSm, was the field-normalized citation impact measure developed at the Centre for Science and Technology Studies (CWTS) in Leiden and described by Moed, De Bruin, and Van Leeuwen in 1995. It compares a unit's observed citation rate with what would be expected given the fields, document types, and years in which it published. Specifically, it divides the citations per publication (CPP) by the mean field citation score (FCSm), forming a ratio in which a value of 1 marks performance exactly at the field average. For more than a decade it was CWTS's flagship indicator, until Waltman and colleagues showed in 2011 that its ratio-of-averages construction had statistical drawbacks and proposed the MNCS as a successor.	The e-index, proposed by Chun-Ting Zhang in 2009, isolates the citations that the h-index throws away. Inside the h-core of an author's h most-cited papers, the h-index implicitly credits each paper with only h citations and discards everything above that, even though top papers may have far more. The e-index recovers exactly this surplus: it is the square root of the difference between the total citations of the h-core and the h-squared citations that the h-index already accounts for. Zhang designed it as a complement rather than a replacement for the h-index, so that the pair (h, e) together describe both the size of an author's productive core and the concentration of excess impact within it.