Improving Relevance

This topic describes some of the ways that you can adjust the settings used in ranking calculation for Enterprise Search results, as well as other techniques you can try for improving relevance.

Considerations When Adjusting Relevance Settings

Before you modify relevance settings, it is essential that you establish a testing system for comparing results before and after you make changes, so that you can validate whether the changes had a negative impact, positive impact, or no impact on search results relevance in your environment.

Search Administrator Tasks

Search administrators can perform several tasks that affect relevance at the Shared Service Providers (SSP) administration level and the Site administration level.

Authoritative Pages

Authoritative pages are identified by search administrators as the pages that link to the most relevant information regardless of the query. You can increase the rank calculated for a set of content using authoritative pages by ensuring that the click-distance from authoritative pages to the content is low.

You can manage the Authoritative pages list using the SSP Administration user interface, or you can use the Search Administration object model. For information about using the object model, see Developer Tasks.

Demoted Sites

Demoted sites contain content that is less relevant than other content for any query; for example, sites with stale content that still must be included in the content index. If you add a site to the Demoted sites list for an SSP, all content within that site is ranked lower than other content.

You can manage the Demoted sites list using the SSP Administration user interface, or you can use the Search Administration object model. For information about using the object model, see Developer Tasks.

Editorial Results

Keywords are words or phrases that the organization has identified as important. You can add keywords at the Site administration level, and use them to display additional information and recommended links on the initial results page that would not otherwise be displayed in the search results for queries containing that keyword term. Two pieces of information can be displayed for a keyword—a definition of the term, and the best bets, which are a list of links identified as being very relevant for that term.

You can manage the keywords list through the Site Settings administration user interface, or you can use the Search Administration object model. For information about using the object model, see Developer Tasks.

Developer Tasks

Enterprise Search in Microsoft Office SharePoint Server 2007 includes a new Search Administration object model for administering Enterprise Search. The objects described in this section are part of the Administration object model. For information about the new object model, see Getting Started with the Enterprise Search Administration Object Model.

Relevance Object Model

Enterprise Search provides a new Relevance object model for modifying the parameters used in the rank calculation for search results relevance.

The entry point for modifying Enterprise Search relevance parameters is the Ranking class. When you initialize an instance of the Ranking class, you pass a SearchContext object as a parameter in the constructor.

Authoritative Pages

The AuthorityPages property of the Ranking class returns an AuthorityPageCollection object that represents a collection of all the authoritative pages for the SSP. The AuthorityPage class represents a single authority page.

Demoted Sites

The DemotedSites property of the Ranking class returns a DemotedSiteCollection object that represents a collection of all the demoted sites for the SSP. The DemotedSite class represents a single demoted site.

Ranking Parameters

The RankingParameters property of the Ranking class returns a RankParamCollection object that represents a collection of all the ranking parameters for the SSP. The RankingParameter class represents a ranking parameter site.

You can update the values specified for the ranking parameters, but you cannot add, delete, or rename parameters.

The Enterprise Search ranking parameters are described in the following table.

Parameter Description

k1

Saturation constant for term frequency.

Kqir

Saturation constant for click distance.

wqir

Weight of click distance for calculating relevance.

Kud

Saturation constant for URL depth.

wud

Weight of URL depth for calculating relevance.

languageprior

Weight for ranking applied to content in a language that does not match the language of the user.

filetypepriorhtml

Weight of HTML content type for calculating relevance.

filetypepriordoc

Weight of Microsoft Office Word content type for calculating relevance.

filetypepriorppt

Weight of Microsoft Office PowerPoint content type for calculating relevance.

filetypepriorxls

Weight of Microsoft Office Excel content type for calculating relevance.

filetypepriorxml

Weight of XML content type for calculating relevance.

filetypepriortxt

Weight of plain text content type for calculating relevance.

filetypepriorlistitems

Weight of list item content type for calculating relevance.

Filetypepriormessage

Weight of Microsoft Outlook e-mail message content type for calculating relevance.

Schema Object Model

Changing the Property Weight

You can modify the weight setting for any managed property in Enterprise Search. For a code sample that demonstrates how to do this, see How to: Change the Weight Setting for a Managed Property.

NoteNote:

The Microsoft Office SharePoint Portal Server 2003 version of the SQL search syntax supported column weighting at query time. The Enterprise Search in Microsoft Office SharePoint Server 2007 version of the SQL search syntax, however, does not support column weighting. If column weighting is present in search queries you migrate to Office SharePoint Server 2007, the search queries will still work, but the column weighting values will be ignored.

The property weight value is set in the Weight property of the ManagedProperty class.

Changing the Length Normalization for a Property

You can modify the length normalization setting for any managed property in Enterprise Search.

The property length normalization value is set in the LengthNormalization property of the ManagedProperty class. For information about managed properties, see Managing Metadata.

Keyword Object Model

Enterprise Search provides a Keyword object model for working with keywords, best bets, and definitions. You can promote sites and information that would otherwise not be included in search results for a particular search term or phrase.

The entry point to the Keyword object model is the Keywords class. Use the AllKeywords property of the Keywords class to retrieve the collection of keywords associated with a particular site. To retrieve the site's collection of best bets, use the GetAllBestBets method. This method returns a BestBetCollection containing the BestBet objects that represent the site's best bet collection.

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