The Why Rank feature returns information that describes which relevance ranking modules were evaluated during a query and describes how query results were ranked. This information allows an application developer to debug relevance ranking behavior.
With Why Rank enabled in an application, the MDEX Engine returns records
that are augmented with additional dynamically generated properties. The MDEX
Engine also a returns summary information (in a
Supplement
object) about relevance ranking for a query.
The properties provide information that describe which relevance ranking
modules ordered the results and indicate why a particular record was ranked in
the way that it was.