anchor.diff:  All of this information, together with meta information about the user (e.g. the browser, location, earlier preferences etc...) then gets translated into a query to the underlying search system.
   
   The challenge for search engineers is to tweak this translation process from user entries to a concrete query in such a way, that the search results contain the most relevant information with respect to the users information_need.
  -This can only be done if the search result quality is evaluated constantly across a representative test suit of typical user queries, so that improvements in the rankings for one particular query doesn't negatively effect the ranking for other types of queries.
  -
  -In order to get started with search quality evaluation, three basic things a needed:
  -
  -. a collection of document you want to evaluate your query performance against, usually one or more indices
  +This can only be done if the search result quality is evaluated constantly across a representative test suite of typical user queries, so that improvements in the rankings for one particular query doesn't negatively effect the ranking for other types of queries.
  +
  +In order to get started with search quality evaluation, three basic things are needed:
  +
  +. a collection of documents you want to evaluate your query performance against, usually one or more indices
   . a collection of typical search requests that users enter into your system
   . a set of document ratings that judge the documents relevance with respect to a search request+
     It is important to note that one set of document ratings is needed per test query, and that
  
positive.code: ------------------------------
  // NOTCONSOLE
  
  <1> a set of typical search requests to your system
  <2> definition of the evaluation metric to calculate
  <3> a specific metric and its parameters
  
  
negative.code: [cols="<,<",options="header",]
  |=======================================================================
  |Parameter |Description
  |`relevant_rating_threshold` |Sets the rating threshold above which documents are considered to be
  "relevant". Defaults to `1`.
  |=======================================================================
  
  