Compare methods

	Patent–Paper Citation Linkage (NPL)	Disruption Index (CD-Index)
Field	Bibliometrics	Bibliometrics
Family	Process / pipeline	Process / pipeline
Year of origin	1997	2017
Originator	Francis Narin, Kimberly S. Hamilton & Dominic Olivastro	Russell J. Funk & Jason Owen-Smith; Lingfei Wu, Dashun Wang & James A. Evans
Type	Citation-linkage pipeline connecting patents to scientific literature	Citation-network pipeline for classifying contributions as disruptive or consolidating
Seminal source	Narin, F., Hamilton, K. S., & Olivastro, D. (1997). The increasing linkage between U.S. technology and public science. Research Policy, 26(3), 317-330.	Funk, R. J., & Owen-Smith, J. (2017). A Dynamic Network Measure of Technological Change. Management Science, 63(3), 791-817.
Aliases	Science Linkage Analysis, Non-Patent Literature Analysis, NPL Citation Analysis, Patent-to-Science Citation Linkage	CD Index, Consolidation-Disruption Index, CD5 Index, Disruptiveness Measure
Related	3	3
Summary	Patent–paper citation linkage measures how strongly technology draws on science by analyzing the non-patent literature, or NPL, references that appear on patents. When a patent cites a scientific journal article rather than another patent, it leaves a traceable thread connecting an invention to the research it built on. Francis Narin, Kimberly Hamilton, and Dominic Olivastro's landmark 1997 study traced these threads at national scale and found that the citation linkage between U.S. patents and scientific papers was growing rapidly, that the cited science was overwhelmingly public, authored in universities and government laboratories, and that this linkage offered a quantitative measure of the contribution of public science to industrial technology. The resulting science-linkage indicator distinguishes science-intensive technologies from incremental ones and underpins studies of how publicly funded research feeds private innovation.	The disruption index, or CD index, classifies a scientific paper or patent by how the work that cites it treats the work it built on. Introduced by Russell Funk and Jason Owen-Smith in 2017 as a dynamic network measure of technological change, and popularized for science by Lingfei Wu, Dashun Wang, and James Evans in 2019, it asks a simple structural question: when later researchers cite a focal work, do they also keep citing that work's own references, or do they cite the focal work instead of its predecessors? If subsequent work cites the focal item but largely ignores its references, the item has disrupted its field, eclipsing what came before; if subsequent work cites both the item and its references together, the item has consolidated existing knowledge. The index runs from -1 (purely consolidating) to +1 (purely disrupting) and has become a standard tool for measuring whether contributions push science in new directions or deepen established lines.