[Corpora-List] Precision and Recall

[Federica Barbieri]

Hi all, 
I just wanted to thank all those -- too many to be mentioned -- who have 
answered to my query on precision and recall. I could not expect to get so 
much useful information!

Federica

>===== Original Message From Paul Clough <p.d.clough at sheffield.ac.uk> =====
>There's also an excellent summary of evaluation measures (for IR) in this new
>book:
>
>Search Engines: Information Retrieval in Practice. Books. Croft, W. B., 
Metzler,
>D. and Strohman, T., Pearson Education (expected 2009).
>
>Fortunately you can download the evaluation chapter as one of the samples 
here:
>
>http://www.pearsonhighered.com/croft1epreview/samples.html
>
>
>Paul.
>
>
>-------------------------------------------------------
>Dr. Paul Clough (Lecturer in Information Systems)
>
>Department of Information Studies
>University of Sheffield
>Regent Court
>Sheffield S1 4DP
>Tel: +44 (0)114 2222664
>Fax: +44 (0)114 2780300
>Email: p.d.clough at sheffield.ac.uk
>Web: http://ir.shef.ac.uk/cloughie/
>-------------------------------------------------------
>
>
>Quoting Adam Funk <a.funk at dcs.shef.ac.uk>:
>
>> [18/04/08 08:39] Daniel Zeman wrote:
>> > Thierry Fontenelle napsal(a):
>> >> Precision: The number of correct responses divided by the total number
>> >> of actual responses.
>> >>
>> >> Recall: The number of correct responses divided by the total number of
>> >> possibly correct responses.
>>
>> > Alternative wording I usually tell my students:
>> >
>> > P = number of things I correctly found / number of things I found
>> > R = number of things I correctly found / number of things I should have
>> > found
>> >
>> > ("correctly found" = "I found it" AND "I should have found it")
>>
>> Here's another way to look at it, which I sometimes find useful:
>>
>> P = true_positives / (true_positives + false_positives)
>>
>> R = true_positives / (true_positives + false_negatives)
>>
>>
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>>
>
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+++++++++++++++++++++++++++++++++++++
Federica Barbieri
PhD Candidate in Applied Linguistics
English Department
Northern Arizona University
Flagstaff, AZ 86001-6032

E-mail: Federica.Barbieri at NAU.EDU
+++++++++++++++++++++++++++++++++++++



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