Searching the Literature Concepts Resources Searching Skills Victoria

Searching the Literature: Concepts, Resources & Searching Skills Victoria H. Goode, MLIS Clinical Informationist Welch Medical Library vgoode 1@jhmi. edu

Today’s agenda • Search process overview • Important Database features • Some major databases other than Pub. Med – esp. important to include in systematic review searching • Why controlled vocabulary searching is key • Controlled vocabulary searching in Pub. Med • Pub. Med searching techniques and mechanics • Clinical Queries and Google Scholar • Reminders – final thoughts

Effective Literature Searching: the steps 1. Identify your topic (and write it down!) 2. Identify applicable resources 3. Create a list of controlled vocabulary terms, synonyms and related terms 4. Conduct your search 5. Record you findings 6. Critically evaluate the information

Literature searching - process overview • Steps: – Define the purpose of your search – Form your question • Write it down! – Now identify relevant databases and resources – Create a search query from your question – for use within a specific database! • Identify the key concepts (often 2 -3 sometimes more) in your question • Find searchable terms for those concepts: most specific controlled vocabulary terms as well as keyword phrases • Group into distinct sets the terms that represent/describe each main concept with Boolean “OR” • Combine sets with Boolean “AND”

Literature searching - process overview (cont. ) – Run your search query – Revise the query until you are satisfied Remember, a good search query usually incorporates controlled vocabulary terms from the database, when there is a controlled vocab. , as well as keywords/phrases. – Record and store your findings Strategy can be saved in My. NCBI & in Word Documents – good for making notes to self; citations can be saved in Ref. Works or other citation management programs. – Revisit/revise the search query for each distinct database you search – Evaluate the findings • Critically appraise the articles

Get to know your databases’ features Does a database include/allow: • • • automatic term mapping? a controlled vocabulary for use in searching? vocabulary designated as major focus? Boolean operators (AND, OR, NOT) adjacency or proximity searching? required special syntax – e. g. “around keyword phrases” in Pub. Med to override automapping; ‘around keyword phrases’ in EMBASE. • field tag searching? -- e. g. [tiab] in Pubmed

Database-specific Controlled Vocabularies Some major databases: – – – – – Pub. Med Cochrane Library EMBASE Web of Science SCOPUS Psyc. Info Global Health CINAHL ERIC Has controlled vocabulary? Me. SH YES -- “EMTREE” No No YES – “Thesaurus” YES – “CINAHL Headings ” YES – “Descriptors”

What’s the big deal with controlled vocabulary? • It provides a consistent, precise way to retrieve information when different natural language words/phrases (synonyms) are used for the same concept, or when the same natural language is used for different concepts! (e. g. “cold” Which meaning? ) • Controlled vocabulary terms control for spelling variations (think British v. Am. English), plurals, acronyms. • Why do we say cont. vocab. searching is precise? – because only articles indexed with that vocabulary term are retrieved. • Select the most specific cont. vocab. term available for your concept; that’s how indexers apply them!

Controlled vocabulary in Pub. Med • Me. SH (Medical Subject Headings) – NLM’s controlled vocabulary to search Medline (Pub. Med) – Over 22, 000 terms – Don’t guess – check the Me. SH Database for what the controlled vocabulary term is for your concept. Natural language: Health screening Emergency department Computed tomography SARS Reproductive health Me. SH Term: Mass Screening [Me. SH] Emergency Services, Hospital [Me. SH] Tomography, X-Ray Computed [Me. SH] SARS Virus [Me. SH]; Severe Acute Respiratory Syndrome [Me. SH] Reproductive Medicine [Mes. H]; Reproductive Health Services [Me. SH]

Pub. Med searching specifics • Always look at the “Details” box: – Find out what the automatic mapping behind the scenes did to the keywords/phrases you put in the search box. – What’s in the details is the query. – You can amend the query in this view – but… – It’s often easier to just override the mapping by selecting your own “building blocks” – a combo of Me. SH headings & possibly keyword phrases -- and then combining them in Advanced Search. But first…

What is your question? Write it down so you can identify its components

One method might be to use PICO format • PICO is a format to organize your thoughts: What is the Patient, Intervention, Comparison, Intervention, Outcome(s) of interest to me?

Or you can write out your question and circle your main concepts • E. g. “What are the treatment margins being used in stereotactic body radiotherapy for lung cancer? ” Identify main concepts: (Concept 1) margins (Concept 2) stereotactic body radiotherapy (Concept 3) lung cancer

Now we translate the main concepts from your question into a searchable query

Concepts to Query (Concept 1) margins (Concept 2) stereotactic body radiotherapy (Concept 3) lung cancer Becomes: (margin*) AND (Radiosurgery [Me. SH] OR “stereotactic body radiotherapy” OR “SBRT” OR “body radiosurgery” OR “extracranial radiosurgery”) AND (lung neoplasms [Me. SH] OR “lung cancer”)

Now let’s walk through the mechanics of how to do that in Pub. Med… • How to force keyword strings – double quotes • How to send terms from Me. SH database to Pub. Med and run the search • How to combine concept sets with Boolean operators • Open a My. NCBI account (important for saving searches AND NIH Public Access Policy Compliance – Bibliography Management)

A quick bit on Pub. Med Clinical Queries interface • Great for clinical questions. Quickly connect to evidencebased literature within Pub. Med. • Can search by clinical study category or search for systematic reviews. • It’s called an evidence-based resource due to the behind -the-scenes “filters” or search algorithms; developed by librarian/physician teams at Mc. Master – and tested in information retrieval studies. • Using Me. SH in this interface is more precise, too.

A word on Google Scholar • Has no controlled vocabulary – if Google changes its algorithm, there’s no guarantee you’ll get the same results when you search. • No unique identifier (like a PMID) for each record: you might get different version of an item/article if you repeat your search at another time. • Can’t sort results by date. • The full-text you find depends on to what your institution subscribes, so what you find will vary depending on where you do your search (on campus or through VPN vs. at another university, hospital, Internet café in Thailand). Scientific methods, including your SEARCHING METHODS, must be reproduceable. Do not use Google Scholar formal searching.

Reminders -- final thoughts Testing/revising your search strategy: – It’s not about the number of hits per se. – It’s whether the strategy captured on-topic target articles – but not too many off-topic articles. It’s a trade-off: precision v. recall (kind of like specificity v. sensitivity) – Read a random sample of abstracts from your results. – Investigate why you got outlier articles. – Review the record for an on-topic article from your results to see the controlled vocabulary terms (e. g. in “Medline” display in Pub. Med) that were applied.

Reminders -- final thoughts (cont. ) • Continue to review your question – has it changed/evolved? • Write it down • Break out searchable concepts to create sets of terms • Consult an expert searcher* -- your department’s assigned informationist for your literature searches. • Invite her or him to be a team member, esp. on systematic reviews and content analyses, where the search results are the critical “inputs” for the project. http: //www. welch. jhu. edu/liaison/index. html

Questions? "As a statistician, I've often told clinicians that "We are the experts at analyzing data, please come to us for help, or let us do it for you. Don't just do it yourself, you might miss something. " It was nice to hear the librarians tell me the same thing. They are the experts at searching the literature; we should go to them for help and not do it ourselves. ” Marta Marsh Gilson, Ph. D, Assistant Professor, SOM, Surgery