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From "Dave Kor" <>
Subject Re: Lucene's Mean Average Precision
Date Thu, 15 May 2008 11:19:24 GMT
I haven't participated in TREC for the past 2 years, so I am wonder which
TREC track were you comparing your results against? The last time I checked,
Lucene's score for the Terabyte track wasn't wonderful, but it was still
pretty decent.

Bear in mind that Lucene uses the plain old vanilla TF-IDF formula to score
documents. That is, Lucene simply assumes that if a search term appears
often in a short document, then that document would be ranked very highly.
Lucene by itself does not do query expansion (although it is relatively easy
to add Rocchio's algorithm), nor any of the other stuff that modern search
engines do.

On Mon, May 5, 2008 at 2:13 AM, DanaWhite <> wrote:

> Hello all,
> I have been doing some evaluation of Lucene on a TReC collection and get a
> rather disappointing mean average precision (MAP) of 11%.  Other sources
> seem to report a MAP of about 20%.
> So I am here to ask all of you who have done some Lucene evaluation - what
> did you find Lucene's MAP to be?  Did you do anything to special (e.g.
> query
> expansion) to get it higher?
> Thanks
> Dana
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Dave Kor

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