1. Reference Collections: Collection Characteristics

2. CACM Collection 3204 Communications of the ACM articles Focus of collection: computer science Structured subfields: –Author names –Date information –Word stems from title and abstract –Categories from hierarchical classification –Direct references between articles –Bibliographic coupling connections –Number of co-citations for each pair of articles

3. CACM Collection 3204 Communications of the ACM articles Test information requests: –52 information requests in natural language with two Boolean query expressions –Average of 11.4 terms per query –Requests are rather specific with an average of about 15 relevant documents –Result in relatively low precision and recall

4. ISI Collection 1460 documents from the Institute of Scientific Information Focus of collection: information science Structured subfields: –Author names –Word stems from title and abstract –Number of co-citations for each pair of articles

5. ISI Collection 1460 documents from the Institute of Scientific Information Test information requests: –35 information requests in natural language with Boolean query expressions –Average of 8.1 terms per query –41 information requests in NL without Boolean query expression –Requests are fairly general with an average of about 50 relevant documents –Higher precision and recall

6. Observation Collection# of Docs# of TermsTerms/Doc CACM32041044640.1 ISI14607392104.9 Number of terms increases slowly with number of documents

7. Cystic Fibrosis Collection 1239 articles with “Cystic Fibrosis” index in MEDLINE Structured subfields: –MEDLINE accession number –Author –Title –Source –Major subjects –Minor subjects –Abstract (or extract) –References in the document –Citations to the document

8. Cystic Fibrosis Collection 1239 articles with “Cystic Fibrosis” index in MEDLINE Test information requests: –100 information requests –Relevance assessed by four experts with a scale of 0 (not relevant), 1 (marginal relevance), and 2 (high relevance) –Overall relevance is sum (0-8)

9. Discussion Questions In developing a search engine: –How would you use metadata (e.g. author, title, abstract)? –How would you use document structure? –How would you use references, citations, co-citations? –How would you use hyperlinks?