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https://issues.apache.org/jira/browse/TIKA-369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14342531#comment-14342531
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Ken Krugler commented on TIKA-369:
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Hi Tyler - detection speed is an issue, but Tika also suffered from accuracy.
In Mike McCandless's tests, Tika was both 10x slower than language-detection,
and had about a 3.5x higher error rate IIRC (2.8% error rate vs. 0.8%).
I think this issue should be left open, as it has interested details on
possible replacements for the current code that I don't think we want to lose.
> Improve accuracy of language detection
> --------------------------------------
>
> Key: TIKA-369
> URL: https://issues.apache.org/jira/browse/TIKA-369
> Project: Tika
> Issue Type: Improvement
> Components: languageidentifier
> Affects Versions: 0.6
> Reporter: Ken Krugler
> Assignee: Ken Krugler
> Attachments: Surprise and Coincidence.pdf, lingdet-mccs.pdf,
> textcat.pdf
>
>
> Currently the LanguageProfile code uses 3-grams to find the best language
> profile using Pearson's chi-square test. This has three issues:
> 1. The results aren't very good for short runs of text. Ted Dunning's paper
> (attached) indicates that a log-likelihood ratio (LLR) test works much
> better, which would then make language detection faster due to less text
> needing to be processed.
> 2. The current LanguageIdentifier.isReasonablyCertain() method uses an exact
> value as a threshold for certainty. This is very sensitive to the amount of
> text being processed, and thus gives false negative results for short runs of
> text.
> 3. Certainty should also be based on how much better the result is for
> language X, compared to the next best language. If two languages both had
> identical sum-of-squares values, and this value was below the threshold, then
> the result is still not very certain.
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