Google Search Appliance Creating the Search Experience - Manual (Page 71)

Google Search Appliance: Creating the Search Experience Best Practices 71
In the front end for staff, you do not create a result biasing policy. This front end preserves normal
ranking.
You can also specify how quickly documents' scores are decreased as they age, by selecting an age at
which you would consider a document to be moderately old. This setting indicates that a document of
the specified age should get a moderate decrease in score from date biasing. More recent documents
get smaller date biasing effects, and documents older than that age get larger decreases in score.
For example, if you select “a day” as the age at which documents become moderately old, then
documents that are a day old receive a moderate decrease in score from date biasing, and documents
much older than that quickly get nearly the maximum effect of date biasing. On the other hand, if you
choose “a year” as a moderately old age, then documents that are a year old get a moderate score
decrease, those that are a few months old get their score decrease slightly, while documents that are a
day old get very little date biasing effect.
In general, a good starting point for using this parameter is to think about some queries your users
might issue and the types of pages they would get back. Consider how old a result would have to be
before it is likely to be obsolete compared to pages authored or modified more recently. That age may
be a reasonable setting for a document to be considered “moderately old,” although experimenting with
different settings is the best way to find out how it affects your search results.
The date biasing feature does not provide results that are ordered strictly by date, because other
factors are considered in a document's score. To order results strictly by date, any user can click the Sort
by date link.
Date biasing is applied to search results in a flexible manner. To experiment with the settings to see how
it affects the documents in your index. You'll typically notice that date biasing affects the order of recent
documents with small differences in date more than it affects older documents with small differences in
date.
Which Document Dates Are Used for Date Biasing?
The document date that the Google Search Appliance evaluates for date biasing is specified on the
Crawl and Index > Document Dates page. For example, the search appliance can use one of the
following dates:
• The last modified date of the document
• A date in the URL
• A date in the document title
However, if a document is added to the index by a feed rather than by a crawl, the document might not
have a useful associated date for use with date biasing.
Using Metadata and Entity Biasing
Using metadata and entity biasing, you can boost or weaken the relevancy score of a document based
on metadata or entities associated with a document. Boosting a score usually moves a result up in the
rankings. Weakening a score usually moves it down. The search appliance offers two controls over
metadata and entity biasing, as described in the following table.
Control Description
Influence Specifies how much influence metadata and entity biasing has in calculating scores
for results rankings overall. The default influence is No influence. You can change
this to one of ten settings in a range of More influence for a search appliance.