why do i get different results ?
DESCRIPTION
Why do I get different results ?. Terry Ann Jankowski, MLS, AHIP Head, User Experience Health Sciences Library University of Washington. Short Answer. Different d atabases Term selection. Different Databases. Coverage Years covered Journals & publication types Update schedule - PowerPoint PPT PresentationTRANSCRIPT
Why do I get different results ?
Terry Ann Jankowski, MLS, AHIPHead, User ExperienceHealth Sciences Library
University of Washington
Short Answer• Different databases• Term selection
Different Databases• Coverage– Years covered– Journals & publication types– Update schedule
• Structure– Default fields– Default operations
CoverageNLM PubMed/Medline• 1946 –• Daily (Tues – Sun)
Ovid Medline• Depends • Depends
What happens when you type
frozen shoulder
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
What happens when you type
frozen shoulder*
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
What happens when you type
“frozen shoulder”
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
You can control results by• Getting to know your database• Using qualifiers• Term selection
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
Indexing PrinciplesEntire articleAvg 10 – 15/20Major vs minorUse most specific term or closest match – Rule of 3Drugs – generic (USAN)Techniques, methods & geography – minor onlyNeoplasms - site & histological typeSpecialty terms
Indexing Rules of Thumb• Pre-coordinated• Heading/sub heading combination(s)• 2 or more unrelated terms
Warning• Inconsistency in indexing
Question
• What is the effect of estrogen and progesterone on the brain, particularly in regards to epilepsy?
Natural Language Strategy
Brain AND (estrogen OR progesterone) AND (epilepsy OR seizures)
Controlled Vocabulary Search(brain/de OR brain/ci) AND (estrogens OR progesterone) AND (epilepsy/ci OR epilepsy/ci)
CompareBrain-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. PMID: 22835430 [PubMed - indexed for MEDLINE]
Which will you use?
Final Thoughts• Experiment to find the best search• Use the database structure and features to
your advantage• KNOW YOUR DATABASE