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From "Yonik Seeley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1534) idf(t) is not actually squared during scoring?
Date Mon, 02 Feb 2009 21:53:59 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12669756#action_12669756
] 

Yonik Seeley commented on LUCENE-1534:
--------------------------------------

{quote}
EG for a single TermQuery, the queryWeight will always be 1.0 (except
for roundoff errors), cancelling out that idf factor, leaving only one
idf factor?
{quote}

Yes, for a score returned to the user only one idf factor remains because of the normalization.
*But* the more important part of the scoring is how terms are scored relative to each other
in the same query - and that is still idf**2

> idf(t) is not actually squared during scoring?
> ----------------------------------------------
>
>                 Key: LUCENE-1534
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1534
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Query/Scoring
>    Affects Versions: 2.1, 2.2, 2.3, 2.3.1, 2.3.2, 2.4
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>            Priority: Minor
>             Fix For: 2.9
>
>
> The javadocs for Similarity:
>   http://lucene.apache.org/java/2_4_0/api/org/apache/lucene/search/Similarity.html
> show idf(t) as being squared when computing net query score.  But I
> don't think it is actually squared, in looking at the sources?  Maybe
> it used to be, eg this interesting discussion:
>   http://markmail.org/message/k5pl7scmiac5wosb
> Or am I missing something?  We just need to fix the javadocs to take
> away the "squared"...

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