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Why do I get different results ? Terry Ann Jankowski, MLS, AHIP Head, User Experience Health Sciences Library University of Washington
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Short Answer Different databases Term selection
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Different Databases Coverage – Years covered – Journals & publication types – Update schedule Structure – Default fields – Default operations
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Coverage NLM PubMed/Medline 1946 – Daily (Tues – Sun) Ovid Medline Depends
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What happens when you type frozen shoulder
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NLM “All fields” Automatic term mapping to MeSH Automatic explosion of MeSH terms Words “anded” Ovid “mp” – default fields No term mapping No explosion Words searched as a phrase
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What happens when you type frozen shoulder*
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NLM “All fields” No term mapping to MeSH No explosion of MeSH terms Words searched as phrase Ovid “mp” – default fields No term mapping No explosion of MeSH Words searched as phrase
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What happens when you type “frozen shoulder”
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NLM Phrase index searched No explosion of MeSH terms Words searched as phrase (may or may not be “anded”) Ovid “mp” – default fields No term mapping No explosion of MeSH Words searched as phrase
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You can control results by Getting to know your database Using qualifiers Term selection
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What terms to use? Natural language Quick & dirty searching New words, brand names, phrases Concepts not indexed Controlled Vocabulary More comprehensive? Concepts not words Pre-coordination
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Indexing Principles Entire article Avg 10 – 15/20 Major vs minor Use most specific term or closest match – Rule of 3 Drugs – generic (USAN) Techniques, methods & geography – minor only Neoplasms - site & histological type Specialty terms
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Indexing Rules of Thumb Pre-coordinated Heading/sub heading combination(s) 2 or more unrelated terms
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Warning Inconsistency in indexing
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Question What is the effect of estrogen and progesterone on the brain, particularly in regards to epilepsy?
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Natural Language Strategy Brain AND (estrogen OR progesterone) AND (epilepsy OR seizures)
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Controlled Vocabulary Search (brain/de OR brain/ci) AND (estrogens OR progesterone) AND (epilepsy/ci OR epilepsy/ci)
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Compare Brain-derived neurotrophic factor-estrogen interactions in the hippocampal mossy fiber pathway: Implications for normal brain function and disease.Brain-derived neurotrophic factor-estrogen interactions in the hippocampal mossy fiber pathway: Implications for normal brain function and disease. PMID: 23276673 [PubMed - in process] Finasteride inhibits the disease-modifying activity of progesterone in the hippocampus kindling model of epileptogenesis.Finasteride inhibits the disease-modifying activity of progesterone in the hippocampus kindling model of epileptogenesis. PMID: 22835430 [PubMed - indexed for MEDLINE]
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Which will you use?
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Final Thoughts Experiment to find the best search Use the database structure and features to your advantage KNOW YOUR DATABASE
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