So sánh phương pháp

	Percentile-Based Citation Impact (PPtop10%)	Immediacy Index
Lĩnh vực	Trắc lượng thư mục	Trắc lượng thư mục
Họ	Process / pipeline	Process / pipeline
Năm ra đời	2011	1972
Người khởi xướng	Lutz Bornmann & Loet Leydesdorff; Ludo Waltman & Michael Schreiber	Eugene Garfield (ISI / Journal Citation Reports)
Loại	Distribution-based citation impact pipeline	Same-year citation-rate pipeline
Công trình gốc	Leydesdorff, L., & Bornmann, L. (2011). Integrated impact indicators compared with impact factors: An alternative research design with policy implications. Journal of the American Society for Information Science and Technology, 62(11), 2133-2146.	Garfield, E. (1972). Citation analysis as a tool in journal evaluation. Science, 178(4060), 471-479.
Tên gọi khác	Percentile Rank Citation Indicators, Top 10% Highly Cited Papers Indicator, PPtop10%, Integrated Impact Indicator (I3)	Journal Immediacy Index, Same-Year Citation Rate, Current Citation Rate, Year-of-Publication Citation Index
Liên quan	3	3
Tóm tắt	Percentile-based citation impact replaces the average citation count with a paper's rank position within a properly defined reference set. Instead of asking how many citations a paper received, it asks where the paper falls in the citation distribution of comparable papers from the same field, year, and document type. Because citation distributions are extremely skewed, a single highly cited paper can inflate a mean, so Lutz Bornmann and Loet Leydesdorff argued that impact should be measured non-parametrically through percentile ranks and the share of papers reaching the top of their field. The most widely used summary is PPtop10%, the proportion of a unit's papers that belong to the most-cited 10% of their reference set; Leydesdorff and Bornmann's Integrated Impact Indicator (I3) generalizes this idea by integrating the full percentile curve. Ludo Waltman and Michael Schreiber clarified how percentile ranks should be computed when many papers share the same citation count.	The Immediacy Index measures how quickly a journal's articles are cited by counting the citations they receive in the very year they are published. Eugene Garfield, who created the Science Citation Index and the impact factor, introduced the immediacy index as part of the Institute for Scientific Information's journal-evaluation methodology and described it in his landmark 1972 Science paper on citation analysis as a tool in journal evaluation. While the impact factor averages citations over a two-year window, the immediacy index uses a zero-year window: it divides the citations made in a given year to that year's articles by the number of citable items published that year. A high immediacy index means a journal's work is picked up almost immediately, the signature of a fast-moving, frontier field or of journals that publish hot, rapidly cited material. It is a measure of citation speed rather than of total impact.