Introduction to Information Retrieval
Introduction to Information Retrieval Introduction to Information Retrieval
Introduction to Information Retrieval Jaccard coefficient: Example • What is the query-document match score that the Jaccard coefficient computes for: • Query: “ides of March” • Document “Caesar died in March” • JACCARD(q, d) = 1/6 10
Introduction to Information Retrieval What’s wrong with Jaccard? • It doesn’t consider term frequency (how many occurrences a term has). • Rare terms are more informative than frequent terms. Jaccard does not consider this information. • We need a more sophisticated way of normalizing for the length of a document. • Later in this lecture, we’ll use (cosine) . . . • . . . instead of |A ∩ B|/|A ∪ B| (Jaccard) for length normalization. 11
- Page 1 and 2: Introduction to Information Retriev
- Page 3 and 4: Introduction to Information Retriev
- Page 5 and 6: Introduction to Information Retriev
- Page 7 and 8: Introduction to Information Retriev
- Page 9: Introduction to Information Retriev
- Page 13 and 14: Introduction to Information Retriev
- Page 15 and 16: Introduction to Information Retriev
- Page 17 and 18: Introduction to Information Retriev
- Page 19 and 20: Introduction to Information Retriev
- Page 21 and 22: Introduction to Information Retriev
- Page 23 and 24: Introduction to Information Retriev
- Page 25 and 26: Introduction to Information Retriev
- Page 27 and 28: Introduction to Information Retriev
- Page 29 and 30: Introduction to Information Retriev
- Page 31 and 32: Introduction to Information Retriev
- Page 33 and 34: Introduction to Information Retriev
- Page 35 and 36: Introduction to Information Retriev
- Page 37 and 38: Introduction to Information Retriev
- Page 39 and 40: Introduction to Information Retriev
- Page 41 and 42: Introduction to Information Retriev
- Page 43 and 44: Introduction to Information Retriev
- Page 45 and 46: Introduction to Information Retriev
- Page 47 and 48: Introduction to Information Retriev
- Page 49 and 50: Introduction to Information Retriev
- Page 51 and 52: Introduction to Information Retriev
- Page 53: Introduction to Information Retriev
<strong>Introduction</strong> <strong>to</strong> <strong>Information</strong> <strong>Retrieval</strong><br />
Jaccard coefficient: Example<br />
• What is the query-document match score that the Jaccard<br />
coefficient computes for:<br />
• Query: “ides of March”<br />
• Document “Caesar died in March”<br />
• JACCARD(q, d) = 1/6<br />
10
Change language