lecture8-evaluation-handout-6-per

E with 1 or harmonic mean is a conservave average

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Unformatted text preview: retrieval want to find something and have a certain tolerance for junk. Introduc)on to Informa)on Retrieval Introduc)on to Informa)on Retrieval   This is not a theorem, but a result with strong empirical confirma)on 13 Sec. 8.3 Difficul)es in using precision/recall 14 Introduc)on to Informa)on Retrieval Sec. 8.3 A combined measure: F   Should average over large document collec)on/ query ensembles   Need human relevance assessments   Combined measure that assesses precision/recall tradeoff is F measure (weighted harmonic mean):   People aren’t reliable assessors   Assessments have to be binary   Nuanced assessments?   Heavily skewed by collec)on/authorship   People usually use balanced F1 measure   Results may not translate from one domain to another   i.e., with β = 1 or α = ½   Harmonic mean is a conserva)ve average 15 Introduc)on to Informa)on Retrieval Sec. 8.3 F1 and other averages   See...
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