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1、Introduction to Searching Bibliographic Databases,Jennifer Lyon,M.S.,M.L.I.S.Eskind Biomedical LibraryVanderbilt University Medical CenterNashville,TN,Some Reasons for Searching the Medical Literature,To answer a specific patient case-related question(practice)To learn more about a medical topic(edu
2、cation)To determine current best practice(guideline)To give the best possible care to patients using evidence-based medicine,Information Overload,PubMed(Medline)contains over 18 million journal citations going back to 1950,*statistics from http:/www.nlm.nih.gov/bsd/bsd_key.html,Techniques for Improv
3、ed Searching,Ability to structure and parse a questionKnowledge of basic database structureUse of Boolean LogicUse of Field SearchingUse of Controlled VocabularySpecialty techniques(truncation,etc.)Consistent step-by-step procedure,Asking the Question:PICO,Patient,Population or Problem What are the
4、characteristics of the patient or population?What is the condition or disease you are interested in?Intervention or exposure What do you want to do with this patient(e.g.treat,diagnose,observe)?Comparison What is the alternative to the intervention(e.g.placebo,different drug,surgery)?Outcome What ar
5、e the relevant outcomes(e.g.morbidity,death,complications)?,http:/healthlinks.washington.edu/ebp/pico.html,Parsing the Question,What are the main concepts in your question?Sample question:Does nutrition therapy improve decubitus(pressure)ulcer healing in an elderly patient?Concepts:,Nutrition therap
6、y,Decubitus/pressure ulcers,Ulcer healing,Elderly patients,Treatment efficacy,A database is an organized collection of data.Bibliographic databases are searched through many of the same techniques as any other databaseFocus will be on PubMed,but these techniques apply to ANY literature database,Exam
7、ples of Records and Fields,Examples of Records and Fields,RED=RECORD BLUE=FIELD PURPLE=ONE PIECE OF DATA,Searching a Database,Different search interfaces do the same things in slightly different waysGood search interfaces should provideAbility to search for a specific item Ability to search for rela
8、ted items to a known itemAbility to search in a specific field or fieldsAbility to combine search terms using Boolean LogicAbility to retrieve search results in a useful way,Boolean Logic,A British mathematician named George Boole(1815-1864)developed an algebraic system of logic that is now widely u
9、sed in computer and electronic systems including database searching.While Booles algebraic system can be complex,a very simple form of Boolean Logic is used for searching most bibliographic databases.,Boolean Operators,Standard Boolean Logic for database searching uses 3 relationships among search t
10、erms.ANDOR NOTIt is both simple and powerful.,AND,BOTH terms included in any results.If a record has only one of the two terms,it will not be retrieved.If the record has neither term,it will not be retrieved.What does this do to the amount of records retrieved?,OR,Only one(NOT both)of the terms are
11、in the resultsOR will retrieve the record if both are included.What does OR do to the amount of records retrieved?,NOT,Excludes any results containing the termRecords containing both will not be retrieved.What does NOT do to the amount of records retrieved?,Using OR,“OR”groupings contain terms for t
12、he same idea/concept and are usually put in parenthesis(term OR term OR term)where all terms are difference ways of representing the same concept(faculty OR teachers OR professors)(students OR learners OR pupils),Using AND,“AND”groupings contain terms for different ideas/concepts and can combine OR
13、groupingsTerm AND(Term OR Term)where each represents a different conceptheart attack AND smokingDiabetes AND exerciseCancer AND(treatment OR therapy),Using NOT,“NOT”statements are usually put last and can contain an“OR”grouping;they are often used to get rid of a common subgroupStudents NOT dentalDi
14、abetes NOT juvenile,Putting Them Together,Identify the concepts(Parse the question)List specific terms for each conceptPut the terms for each concept in an OR statements within parenthesesCombine OR statements with ANDAdd any NOT statements to the end,Creating a Boolean Search,QUESTION:Is Vitamin C
15、helpful in treating the flu?Identify concepts and list terms,Step 2,2.Make your OR statements,one per concept(influenza OR flu OR orthomyxovirus)(vitamin C OR ascorbic acid OR ascorbate)(treatment OR therapy OR management)(outcome OR recovery OR success),Steps 3 and 4,3.Put“AND”between each of the O
16、R statements(influenza OR flu)AND(vitamin C OR ascorbic acid OR orange juice)AND(treatment OR therapy OR management)AND(outcome OR recovery OR success)4.Consider any NOT statements you might want to add.Note:NOT isnt used very often,Parsing a Boolean Search,(emergency OR acute OR critical)AND(treatm
17、ent OR therapy OR management OR care)AND(motor vehicle accident OR car crash)NOT(pedestrian OR walking)What are the four concepts?What terms are used for each concept?Which three concepts must be included in all records found?Which concept must not be included in any record found?,Beyond Basic Boole
18、an,Field SearchingControlled VocabularySubject vs.Keyword SearchingSpecialty FeaturesTruncationPhrase searching,Field Searching,Almost all databases will provide you with some ability to search a specific field or fields.Allows faster searchingAllows more accurate searchingNot all databases may make
19、 all fields searchable.Each search system will require a specific format.,All Field vs.Specific Field Searches,I would like to find articles by John Smith.Search all fields:John Smith Search Author Field only:John SmithI would like to find an article published in 1997.Search all fields:1997Search Pu
20、blication Date Field:1997Why waste time searching for a date in the author field or an author in the volume field?,Formats for Field Searching,Different databases provide different formats for specifying fields.Most use field names or nicknames Field tags OR labelswhich may follow a period or be pla
21、ced in brackets or parentheses.Some databases offer forms or drop-down menus.,PubMedField tags go in and follow termField tags can be used within Boolean queries,PubMed Field Tags,http:/www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=helppubmed.section.pubmedhelp.Search_Field_Descrip,au=authorti=titletw=text
22、wordtiab=title and abstractmh=medical subject heading,dp=date of publicationla=languagegr=grant numberta=journal namead=affiliation,OVID databases require field tags to follow the term separated by a period.Meharry.in and 2005.yr,Some databases,such as the ISIs Web of Science(Science Citation Index
23、Expanded)provide forms to fill out.,Select Field from drop-down menu,Select Boolean Operator,Combining Field Searches,Multiple field searches can be combined using Boolean logic.Find a 2005 article by an author named Hubble about ankle fractures.Combine with AND:2005 in date/year fieldHubble in auth
24、or fieldAnkle fractures in title field,2005dp AND Hubbleau AND ankle fracturesti,Final Notes on Fields,Each database provides its own specific fieldsEach database requires a specific format to designate field searchingWhen searching a new database,take a moment to read the help documentation;most wi
25、ll provide a list of fields and how to search them.,Controlled Vocabulary,A controlled vocabulary is a set of established terms where every term represents a single concept only one term is used for that concept,Another example,How many words could you think of for the idea of“cancer”?Cancer,tumor,m
26、alignancy,neoplasm,sarcomaArticles in a databaseArticle one:“Breast tumors in young women”Article two:“Surgery for prostrate cancer.”Article three:“Diagnosing Melanoma.”All three articles are about types of cancer but different terms are used in titles.,In a controlled vocabulary ONE word(i.e.,cance
27、r)is chosen and placed in a special field,usually called a subject field.For all three articlesArticle one:“Breast tumors in young women”Article two:“Surgery for prostrate cancer.”Article three:“Diagnosing Melanoma.”The subject term(concept term)“cancer”is placed in the subject field by database ind
28、exers.Now,Searching the database for cancer in the subject field will identify all records about the concept of cancer even if a different word for cancer is used.Search cancer-in-subject-field finds all three articlesHow many articles would the search cancer-in-title-field find?,Structure of Contro
29、lled Vocabulary,Broader Concepts,Narrower Concepts,More on Controlled Vocabulary,“Expanding”=Search includes all narrower terms beneath the searched termSome databases do it automatically,others dont“Focusing”or“Majoring”=For a given item,some subject terms are considered the major focus;you can sel
30、ect to return only those articles.Hip fracturemajr=only give me articles where hip fracture is an important concept,Subject vs.Keyword Searching,Controlled vocabulary searching Matches terms against a specific field in the record.You need to consult a thesaurus(paper or online)to find out what the c
31、ontrolled vocabulary term is for each concept.,Free-text(keyword)searching Some concepts have many synonyms.A free-text search statement would mean ORing all those terms togetherMatches terms against words anywhere in record(abstract,title,etc.).,Advantages to Controlled Vocabularies,Using the contr
32、olled vocabulary can make your search more precise and easier.Increases the relevancy of results(fewer false drops)The indexers have already done much of the work for you.Searchable tree structures of terms can help you find new terms to use.,Problems with Controlled Vocabularies,NOT all databases u
33、se a controlled vocabularyNew concepts take time to be added There is often a lag phase during which the newest articles arent indexedControlled vocabularies can contain some very strange things and some concepts may not be handled well The controlled vocabulary must be easily searchableTrying to un
34、derstand what is and isnt in a particular controlled vocabulary can give you a big headache!,Combining Subject and Keyword Searching,To be comprehensive,it is often helpful to combine subject and keyword searching(diabetes mellitusmh OR diabetestw)(sickle cell anemiamh OR sickle cell anaemiati),Dont
35、 forget,Boolean logic to combine termsUse of other search fields in combination with subject termsA Complex Search:(headmh OR headtw)AND(wound and injuriesmh OR traumati OR injuryti)AND 2005dp AND Englishla,Some Specialty Features,TruncationPhrase searchingNeighboring and other rarer Boolean operato
36、rs,Truncation,What about including the singular and plural versions of words as well as other word variations?For example:therapy,therapies,therapeutics,You could combine them all in an OR relationship:(therapy OR therapies OR therapeutics OR therapeutic)But an easier way is by the use of truncation
37、.therap*Each database handles truncation in a unique way.The*and$are the most common wildcard symbols.,More on Truncation,Some examples:Bacter$Proc*Vir?Staph?Be cautious when truncating!If the word stem is too short,there may be too many possible variations and you might pick up unrelated terms.For
38、example,using proc*for finding procaine-like drugs will also include words like proceedings and process.,Phrase Searching,Sometimes you want to force the database to search for a set of words in exact order“fever of unknown origin”Most databases will accept a phrase in quotes.BUTsome do not handle p
39、hrases well and will automatically break them up usually AND-ing the termsCheck how the database handles phrase searching before doing it!,Limits Options,Many databases provide“limits”pages that make it easier for you to select common options such as language,article type,publication dates,human or
40、animal,gender,age groups,etc.Each databases limits options are uniqueMost limits can be done by hand using field tags,but sometimes limit pages save time,PubMed Limits Page,Step-By-Step Search Construction,State the question Identify the concepts in the questionFor each concept,determine keywords an
41、d subject termsSpecify field tags after terms if neededCombine terms for the same concept with“OR”in parenthesisCombine“OR”statements with ANDPut any NOT terms at the endKeep track of your searches,how many articles were found total,and how many you selected as relevant,Example,Question:What is the appropriate ED medical management of adult patients with intracranial hemorrhage(either trauma or spontaneous)?,
