Editing Metasearch engine (section)

=== Fusion ===
[[File:DFIG Model.jpg|thumb|Data Fusion Model|286x286px]]

A metasearch engine uses the process of Fusion to filter data for more efficient results. The two main fusion methods used are: Collection Fusion and Data Fusion.

* Collection Fusion: also known as distributed retrieval, deals specifically with search engines that index unrelated data. To determine how valuable these sources are, Collection Fusion looks at the content and then ranks the data on how likely it is to provide relevant information in relation to the query. From what is generated, Collection Fusion is able to pick out the best resources from the rank. These chosen resources are then merged into a list.<ref name=retrieval/>
* Data Fusion: deals with information retrieved from search engines that indexes common data sets. The process is very similar. The initial rank scores of data are merged into a single list, after which the original ranks of each of these documents are analysed. Data with high scores indicate a high level of relevancy to a particular query and are therefore selected. To produce a list, the scores must be normalized using algorithms such as CombSum. This is because search engines adopt different policies of algorithms resulting in the score produced being incomparable.<ref>{{cite book | last1=Wu | first1=Shengli | last2=Crestani | first2=Fabio | last3=Bi | first3=Yaxin | title=Information Retrieval Technology | chapter=Evaluating Score Normalization Methods in Data Fusion | year=2006 | volume=4182 | pages=642–648 | doi=10.1007/11880592_57 | series=Lecture Notes in Computer Science | isbn=978-3-540-45780-0 | citeseerx=10.1.1.103.295}}</ref><ref>{{cite web | last1=Manmatha | first1=R. | last2=Sever | first2=H. | year=2014 | title=A Formal Approach to Score Normalization for Meta-search. | url=http://maroo.cs.umass.edu/pdf/IR-242.pdf | access-date=2014-10-27 | archive-url=https://web.archive.org/web/20190930051034/http://maroo.cs.umass.edu/pdf/IR-242.pdf | archive-date=2019-09-30 | url-status=dead }}</ref>