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Literature searching: Literature searching - introduction

Literature searching

During the coronavirus crisis librarians continue to offer SVHM staff the following services:

Developing a search strategy in Ovid Medline

Perfect your search in Ovid Medline first

  • Ovid Medline ALL = Pubmed.  You do not need to search both.
  • If you know how to search the Ovid interface then you won't have a problem with Embase, Emcare and PsycINFO. This makes the process EASIER.
  • Do not move on to any other databases until you are completely happy with the Medline search.This will SAVE YOU TIME.
  • Download and print our step by step helpsheet on searching Medline. Have this sitting next to you while you watch our video, which covers the same sample search.
  • After watching the video, login to Ovid Medline and work through the helpsheet step by step yourself, following the sample topic. This will confirm the basic search PROCESS.
  • When you are confident with using subject headings, textwords and combining concepts with AND/OR, use the same technique with your own topic.
  • It will probably take several attempts to refine your search strategy. That is normal.

Be careful about using 'limits' in your searches

Some databases, such as Ovid MEDLINE(R) ALL, include many thousands of non-indexed records and pre-print publications. These new records flood in from electronic publications and there is a time lag before they can be fully indexed or described. The records received from publishers are basic and don't (yet) include subject headings. Of course these non-indexed records include the latest research, so we don't want to lose them.

  • They do not include subject headings - so we have to use text word searches to find them
  • They do not include indexing for human or animal studies - so we lose ALL of the non-indexed records if we 'limit to humans'.
  • They do not include indexing for age ranges or gender or most other automated limits - so we lose ALL of the non-indexed records if we use those limits

There are the only two limits we recommend:

  • English language - works for most old and new records. However some records from the 1980s and 1990s don't index language at all. 
  • date range - these are publication dates included in the basic record

How to exclude animal studies

Don't 'limit to humans'

If you select 'limit to humans' you risk losing all non-indexed and pre-print publications in a database which have not been indexed as 'human'. This could be thousands of records.

Instead, remove the animal studies

A safer alternative is to search for the things we don't want (in this case animal studies) and remove them from the results. Adjust the line numbers below as appropriate.

Ovid Medline

6. [last line of search - your line number will be different]
7. exp animals/ not humans/ 
8. 6 not 7

Ovid Embase and Ovid Emcare

6. [last line of search - your line number will be different]
7. exp animal/ not human/ 
8. 6 not 7

APA PsycINFO  (Ovid)

6. [last line of search - your line number will be different]
7. (animal not human).po. 
8. 6 not 7

CINAHL (EBSCOhost)

S6. [last line of search - your line number will be different]
S7. (MH "Animals+") NOT (MH "Human") 
S8. S6 NOT S7

Recording your search methodology

There are times when you will need to record and share your search methodology, especially in the context of study or writing for publication. In addition to saving your search strategy in the database itself so you can run it again later, we strongly suggest keeping records in a Word document as you go.

Records to keep for a systematic review or similar publication

  • full name of the database
    • eg Ovid MEDLINE(R) ALL 1946 to August 26, 2020.  In Ovid this is available just above the search box
  • full search strategy
    • In Ovid go to your saved search in My Workspace > My Searches & Alerts
    • Click on the 'eye' icon above your saved search to find a format free version of your search strategy to cut and paste.
    • at minimum keep a screenshot that you can type out neatly later
  • date you carried out the search
  • number of results retrieved on that day

It takes very little effort to record this information at the time, but it is impossible to recreate it later.

This is how a record might look for our sample search:

Ovid MEDLINE(R) ALL 1946 to August 28, 2020

Last searched 1 September, 2020 (1200 results)

1. exp *Dementia/    
2. (dementia or alzheimer*).ti,ab.    
3. 1 or 2    
4. *Aggression/    
5. *Violence/    
6. (aggress* or violen*).ti,ab.   
7. 4 or 5 or 6    
8. 3 and 7    
9. limit 8 to (english language and yr="2010 -Current")

This search strategy is easily replicated by another person. Note the inclusion of:

  • both MeSH subject headings and title/abstract textword searches. 
  • neatly grouped concepts
  • use of AND/OR
  • very basic limits - just language and year. See further information for removing animal studies.

If you are searching multiple databases for a review you will need to keep these records for every database you search. Strategies will differ from one database to another due to different subject headings and syntax/commands.

Summary of bibliographic health databases

The following diagram shows the type of content, and a rough idea of the overlap, of key databases. It demonstrates the need for multiple databases to be included in a comprehensive literature search, but it does not attempt to be exact or exhaustive. Databases change constantly and there are many layers of duplication.

Choosing which database to search

Keep in mind that the specialty area of a database is very broad, and it indicates the types of journals indexed rather than the specific content. For example a nursing and allied health database will still include articles on general medicine, psychology and radiology which are published in nursing and allied health journals. Likewise, there are many nursing related topics in Medline and PsycINFO. Medline and Embase cover an extremely wide range of topics.

For most health related systematic reviews we would include:

  • Ovid Medline
  • Ovid Embase
  • Ovid Emcare
  • APA PsycINFO (Ovid)
  • CINAHL (EBSCOhost)
  • Cochrane Library

If you just need to dip in and find a handful of articles in one database (say for a presentation), then we suggest Ovid Medline.

Don't confuse the name of the database with the years of coverage

Database content constantly changes and records are added retrospectively so years of coverage are fluid.

It is important to understand that the years indicated in a database name – such as Ovid MEDLINE(R) ALL <1946 to present> often refer to the date the catalogue started (1946 in this case) and not to the date of the earliest publications indexed in the database, which in Medline go back to the late 1700s.

For many bibliographic databases it is not possible to accurately define the years of coverage. That is why we keep these records for systematic reviews:

  • the full name of the database on the day you searched it eg Ovid MEDLINE(R) ALL 1946 to August 11, 2020 (copy and paste this from the database when you are searching it - in Ovid it sits above the search box)
  • the full search strategy, including any limits
  • the date you carried out the search
  • the number of results you retrieved on that day

Helen Wilding, Senior Research Librarian, St Vincent's Hospital Melbourne, 2020

Searching other databases

Other Ovid databases - Embase, Emcare, APA PsycINFO, Ovid Nursing

  • Translating a search from Ovid Medline to other Ovid databases is quick and easy
  • Use your Ovid Medline search strategy as a cheat sheet.
  • The layout of other Ovid databases will be very similar to Medline, except the subject headings will be different in each database.
  • SEARCH FOR DATABASE SPECIFIC SUBJECT HEADINGS (this is the main difference - for example subject headings in PsycINFO will include more types of counseling and Embase uses European terms and has a focus on pharmaceuticals)
  • Textword search lines will be the same, as long as you have kept to title and abstract fields - you can copy and paste these in
  • The way you group concepts will be the same

CINAHL (EBSCOhost)

  • General process is similar to searching Ovid Medline - grouping concepts and including subject headings and text
  • However the EBSCOhost interface looks a bit different to Ovid - buttons are in different places and syntax (commands) are different
  • Check for CINAHL specific SUBJECT HEADINGS (remembering this database has a nursing focus)
  • Use the Polyglot tool to translate text search lines from Ovid Medline to CINAHL eg haphazard.ti to TI haphazard
  • Group your concepts in the same way as in Ovid Medline
  • See helpsheet for step by step process

Cochrane Library

  • Use Advanced Search > Search Manager 
  • Good news - Cochrane Library uses MeSH like Medline (so you don't have to rethink the subject headings) BUT the syntax (commands) look radically different
  • Use the Polyglot tool to translate text search lines from Ovid Medline to Cochrane Library eg caregivers/ or caregiv*.ti,ab becomes [mh ^caregivers] OR caregiv*:ti,ab
  • Results will be provided in different tabs at the bottom, so make sure you download each set separately to get them all

Informit health databases

  • no subject headings
  • basic keyword searching only

Libguide Author

Helen Wilding, Senior Research Librarian

Carl de Gruchy Library, St Vincent's Hospital Melbourne
+613 9231 2541  Helen.Wilding@svha.org.au

Literature Searching, Systematic Reviews, Mental Health liaison 
Thursdays, Fridays & alternate Wednesdays
Helen's profile | Researchgate | Orcid