| Factoring
in size of a corpus |
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| ¡ | Look at how
P/R or Sn/Sp varies |
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| as a function
of rank: |
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| ¡ | Choose a number
of different |
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| ranks and
calculate P/R or |
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| Sn/Sp |
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| l | Correspond to
vertical lines on |
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| graphs at right |
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| l | Plot Sn vs.
1-Sp to get points for |
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| ROC curve. Interpolate curve. |
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| Irrelevant |
| n |
| 1 |
| Rank |
| Relevant |
| Irrelevant |
