Main path analysis was first proposed by Hummon and Doreian<ref name=":0">{{Cite journal|last=Hummon|first=Norman P.|last2=Doreian|first2=Patrick|date=|title=Connectivity in a citation network: The development of DNA theory|url=https://doi.org/10.1016/0378-8733(89)90017-8|journal=Social Networks|volume=11|issue=1|pages=39–63|doi=10.1016/0378-8733(89)90017-8|via=}}</ref>. It is a mathematical tool to identify the major paths in a [[directedcitation acyclic graphnetwork]] (DAG), typicallywhich is one form of a [[citationdirected networkacyclic graph]] (DAG). The method begins by measuring the significance of all the links in a citation network through the concept of ‘traversal count’ and then sequentially chains the most significant links into a ‘main"main path’path", which is deemed the most significant historical path in the target DAG[[citation network]]. The method is applicable to any human activity that can be organized in the form of a DAG[[citation network]]. The mostmethod commonis applicationscommonly areapplied tracingto trace the knowledge flow paths or development trajectories of a science or technology field, through bibliographic citations or patent citations<ref name=":2">{{Cite journal|last=Liu|first=John S.|last2=Lu|first2=Louis Y.Y.|last3=Lu|first3=Wen-Min|last4=Lin|first4=Bruce J.Y.|title=Data envelopment analysis 1978–2010: A citation-based literature survey|url=https://doi.org/10.1016/j.omega.2010.12.006|journal=Omega|volume=41|issue=1|pages=3–15|doi=10.1016/j.omega.2010.12.006}}</ref><ref>{{Cite journal|last=Verspagen|first=Bart|date=2007-03-01|title=Mapping technological trajectories as patent citation networks: a study on the history of fuel cell research|url=http://www.worldscientific.com/doi/abs/10.1142/S0219525907000945|journal=Advances in Complex Systems|volume=10|issue=01|pages=93–115|doi=10.1142/S0219525907000945|issn=0219-5259}}</ref><ref name=":3">{{Cite journal|last=Lucio-Arias|first=Diana|last2=Leydesdorff|first2=Loet|date=2008-10-01|title=Main-path analysis and path-dependent transitions in HistCite™-based historiograms|url=http://onlinelibrary.wiley.com/doi/10.1002/asi.20903/abstract|journal=Journal of the American Society for Information Science and Technology|language=en|volume=59|issue=12|pages=1948–1962|doi=10.1002/asi.20903|issn=1532-2890}}</ref>. It has also been applied to judicial decisiondecisions to trace the evolving changes of legal opinionopinions<ref name=":4">{{Cite journal|last=Liu|first=John S.|last2=Chen|first2=Hsiao-Hui|last3=Ho|first3=Mei Hsiu-Ching|last4=Li|first4=Yu-Chen|date=2014-12-01|title=Citations with different levels of relevancy: Tracing the main paths of legal opinions|url=http://onlinelibrary.wiley.com/doi/10.1002/asi.23135/abstract|journal=Journal of the Association for Information Science and Technology|language=en|volume=65|issue=12|pages=2479–2488|doi=10.1002/asi.23135|issn=2330-1643}}</ref>.
== History ==
Main path analysis is first propoed in Hummon and Doreian (1989)<ref name=":0" /> in which they suggest a different approach for analyzing a citation network "where the connective threads through a network are preserved and the focus is on the links in the network rather than on the nodes."<ref name=":0" /> They call the resulting chain of the most used citation links "main path" and claim that "It is our intuition that the main path, selected on the basis of the most used path will identify the main stream of a literature." The idea was verified using a set of DNA research articles. To make the method more practical, Liu and Lu (2012)<ref name=":1">{{Cite journal|last=Liu|first=John S.|last2=Lu|first2=Louis Y.Y.|date=2012-03-01|title=An integrated approach for main path analysis: Development of the Hirsch index as an example|url=http://onlinelibrary.wiley.com/doi/10.1002/asi.21692/abstract|journal=Journal of the American Society for Information Science and Technology|language=en|volume=63|issue=3|pages=528–542|doi=10.1002/asi.21692|issn=1532-2890}}</ref> proposedextends the method to include the key-route search. The most useful feature of the key-route search is that one is able to view different level of main paths by adjusting the key-route numbers.
== The method ==
Main path analysis operates in two steps. The first step obtains the traversal countcounts of each link in a DAGcitation network. Several algorithmstypes of traversal counts are mentioned in the literature to calculate traversal count. The second step searches for the main paths by linking the significant links according to the size of traversal counts. Hereafter,One theneeds methodto isprepare explaineda assumingcitation thenetwork thebefore DAGproceeding isfor amain citationpath networkanalysis.
