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From Erik Hatcher <e...@ehatchersolutions.com>
Subject Re: Explanation of Scoring
Date Mon, 10 May 2004 15:40:31 GMT
My guess is that you've used the IndexSearcher.explain method 
incorrectly.  What are you passing to it?  Along with the query, the 
document id should be passed.  If you are iterating over Hits, be sure 
not to pass the hit iteration number.

	Erik


On May 10, 2004, at 9:38 AM, Matthew W. Bilotti wrote:

>
> Hello,
>
> I'm using Lucene 1.4 RC2, and I'm having trouble understanding how the
> scoring relates to document rank.  The work I am doing is going to 
> depend
> very much on knowing exactly how the scoring algorithm works and 
> printing
> out the the score components so that I can analyze contributions of
> individual terms by hand.  If anyone can help me do this, I would be 
> truly
> grateful.
>
> Particularly, I would like help understanding the following strange
> phenomenon:
>
> I executed a query and the first document returned had a score of 
> 0.592.
> The explanation string read "0.0 = match required".  Can anyone tell me
> what this means?
>
> The next 39 documents retrieved had steadily decreasing score with the
> same explanation string.
>
> The 40th document retrieved, though had a score of 1.0 and the 
> explanation
> string:
>
> 0.0 = fieldWeight(contents:invented in 0), product of:
>   0.0 = tf(termFreq(contents:invented)=0)
>   6.507968 = idf(docFreq=4189)
>   0.0390625 = fieldNorm(field=contents, doc=0)
>
> If anyone can help me decipher the explanation strings, or help me to
> understand why a document with score 1.0 is ranked lower than a 
> document
> with score 0.592, or show me how to print out the individual 
> components of
> the score as I am retrieving the documents, please reply.  My work very
> much depends on your help.
>
> Regards,
>
> Matthew Bilotti
>
>
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