19 Oct 2004
CS 5244: Library Evaluation
30
Getting a single number
¡11 pt average
lAverage precision at each .1
interval in recall
l
¡Precision at recall point (% or absolute)
l
¡F Measure
lRatio of precision to recall:              Fb =
l(e.g., F3 = weight precision heavier)
l
l
¡Area under ROC curve (Accuracy)
l1 = perfect, .9 excellent, .5 worthless
¡
¡
(b2+1) PR
 b2P + R
• What’s the difference between these measures?
• Which measures are best suited to which scenarios?
To think about:
    How do we emphasize recall or precision in our F measure
   How do we translate accuracy to precision and recall terms?