Booth 000

How to do a literature search Andrew Booth (University of Sheffield) and Mary Dixon-Woods (University of Leicester)

This course will cover:
The role of the literature review [10 mins]
Types of evidence [5 mins]
Formulating answerable questions [10 mins]
Sources of evidence [12 mins]
Search techniques [30 mins]
Optimal search strategies [10 mins]
Evaluating your literature searching [10 mins]
Evaluation [3 mins]

How to do a literature search
The role of the literature review

The role of the literature review - 1
Exposes main gaps in knowledge [and] identifies principal areas of dispute and uncertainty (Mays et al, 2001).
Helps identify general patterns to findings from multiple examples of research in the same area .
Juxtaposing studies with apparently conflicting findings helps explore explanations for discrepancies .

The role of the literature review - 2
4. Helps define your terminology or identify variations in definitions used by researchers or practitioners.
5. Helps to identify appropriate research methodologies .
6. You can also identify validated scales and instruments.

Case study: Attitudes of different professions to handwashing in a delivery suite - 1
A midwife is researching attitudes of different staff to handwashing. She firstly searches the literature to focus the scope of the original question.
Although the literature on handwashing is vast she needs to discover whether published research has been conducted specifically in obstetrics and gynaecology settings. Has anyone researched the topic specifically in a delivery suite?

“ Handwashing” has many more definitions than she had envisaged.
Does handwashing include the use of a handrub? Does it constitute use of water only? What is the minimum duration of the procedure before it is classed as "handwashing"?
The literature search enables her to explore different definitions of her main concepts.

Are there validated instruments to measure attitudes to handwashing (or towards routine hospital hygiene)?
The literature review may inform selection of appropriate outcomes - those employed in previous studies (literary warrant) or those considered appropriate by the relevant clinical community (user warrant).
Will she focus singly on attitudes or will she investigate knowledge and/or behaviour?

Q: Any other roles or uses for literature review that you have identified?

Types of evidence

Some types of evidence
Prediction – Models, case studies (single and multiple), documentary analysis
Historical – documentary analysis, case studies, narratives
Intervention – experimental studies
Exploration – literature review, theory building, consensus processes
Attitudes – psychological research
Qualitative - using specific qualitative techniques
Causation – observational studies (e.g. case control)

Exercise: What types of “evidence” are relevant to your question?

Formulating answerable questions

Formulating answerable questions
Translates “Aims” into achievable and focused tasks
Helps to distinguish main from subsidiary questions
Helps to identify the likely research designs to answer the research question
Helps in constructing the literature search

Why?
"Ask a poor question and you will get a poor review. A clear question also helps the reader rapidly assess whether the review is relevant to his or her own…practice". (Counsell, 1997)
Clearly framed questions "guide much of the review process including strategies for locating and selecting studies or data, for critically appraising their relevance and validity, and for analysing variation among their results". (Cochrane Handbook)

Some types of question
Prediction – What is the likely result of X?
Historical – How have we got from A to B?
Intervention – Is doing Y better than doing Z?
Exploration – What are the possible explanations for A?
Attitudes – How do people feel about B?
Causation – What are the likely causes of C?
Measurement: What is the size of X, how often does it occur etc?
Characterisation: how can we understand and specify W?

Q: What type of question is your PhD question?

A structure for formulated questions
Health services research uses P ATIENT- I NTERVENTION- C OMPARISON- O UTCOME (PICO) structure
Within social sciences research the following may be more appropriate:
S ETTING
P OPULATION
I NTERVENTION
C OMPARISON
E VALUATION

An example of SPICE [Actual PhD example]
SETTING – UK Marine Conservation
POPULATION – public, private and voluntary sector organisations
INTERVENTION - partnership approaches
COMPARISON – [Unilateral approaches or other countries’ approaches]
EVALUATION – achievement of strategic marine conservation objectives

An example of SPICE [Actual PhD example]
SETTING – UK Television Industry
POPULATION – Women
INTERVENTION – None
COMPARISON – [With men or with other industries]
EVALUATION – historical, political, organisational and practical issues

Try one!
What is the effect of secondary school headteachers’ leadership and management strategies on student achievement, attitudes, behaviour and recruitment?

Exercise: Now you try! Use the SPICE framework to formulate your own research question

Scenario – A fistful of doulas?
You are working on an ESRC funded project looking at the benefits of a doula ( a woman experienced in childbirth who provides continuous physical, emotional, and informational support to the mother before, during and just after childbirth) for low-income mothers.

Our example of SPICE
SETTING – the Developed World (with comparable health systems to the UK)
POPULATION – Low-income mothers
INTERVENTION – Doula (Lay support)
COMPARISON – Professional support [or No Support]
EVALUATION – Perceived levels of social support, birth outcomes, levels of breastfeeding etc.

Sources of evidence

Stages in the literature search process
Focus your question
Decide on the most appropriate sources
Perform a scoping search by:
Dividing your search into a series of ‘concepts’
Thinking of alternative terms for each concept
Searching each concept separately
Combining concepts using Boolean logic
Limiting your search
Revise your search, as necessary, and replicate in other sources

Sources
Electronic databases:
Evidence-based
The Cochrane Library, Clinical Evidence, etc.
Subject specific
ERIC, EconLit, Medline, PsycLit, Cinahl, British Nursing Index, AgeInfo, Biological Abstracts, etc.
Related disciplines
LISA, ASSIA, British Humanities Index, Web of Science (Science, Social Sciences, Arts & Humanities Citation Indexes), etc.

Reflective Exercise
Which of the listed databases might be of relevance to this topic?
[N.B. We are going to search Web of Science and Ovid Medline/CINAHL]

Search techniques

From: Etext on Health Technology Assessment (HTA) Information Resources. Chapter 4: Searching MEDLINE/PubMed for Health Technology Assessment Information by Viveka Alton and Ione Auston. http://www.nlm.nih.gov/nichsr/ehta/chapter4.html

Take Home Message – 1 An optimal search will combine natural language and controlled vocabulary approaches

Natural language
Uses your own words and searches words & phrases (typically from the title, abstract & keyword fields) to retrieve records
Potentially can search any field of a database
Can be very precise (but there can be ambiguities e.g. Moderation [exam process] and Moderation [within reasonable limits] )
Some problems:
Plurals: e.g. child or children
Different spellings: e.g. esthetic or aesthetic
Different terminology: e.g. pavement or sidewalk
Prefixes: prenatal, pre natal, pre-natal

Database features to support natural language
Truncation (e.g. *, $) used to search for different word stems and word endings
e.g. use comput* to find computer, computers, computed, computing, etc. (But comp* would find compost!)
Wild cards (e.g. *, ?) used to search for spelling variants
e.g. use leuk*mia to find leukaemia or leukemia
Proximity and adjacency operators (e.g. adj or near)
e.g. motor near2 accidents

Controlled vocabulary
Maps variations in terminology to a single “approved” word or phrase (e.g. Toyota, Rolls Royce, Mini, Ferrari etc. all mapped to “Automobiles”)
Can demonstrate hierarchical or conceptual relationships (e.g. Europe-UK-England-Hampshire-Southampton)
May not exist for new terms (e.g. “single currency”)
May not map to a precise term (e.g. “teaching techniques” for “problem based learning”)

Database features to support controlled vocabulary
A Thesaurus (e.g. MeSH, ERIC) [NB. Opposite direction to Roget’s Thesaurus – Many-to-One]
Mapping
Explode functions
“ See Under”, “Used For” and “See Also” references

Mapping Vocabulary mapping uses statistical analysis to determine which subject headings (index terms) occur most frequently in documents containing your free text query.

Thesaurus
A controlled vocabulary arranged in a known (e.g. alphabetical or hierarchical) order containing:
Preferred terms (keywords)
non - preferred terms (synonyms ...)
Semantic Relations (Broad Term, Narrow Term, Related Term)
Scope notes

What practical problems would you encounter if you used the following search terms?
Postqualifying (2 problems)
Labour support (3)
PMT (2)
Stroke (2)
Public school (3)
Aids (2)
Adolecent (2)

Take Home Message – 2 Getting unexpectedly few results can be worse than getting no results at all – “satisfied but inept”!

Explosions Pregnancy Childbirth Childbirth, Premature Vaginal Birth Vaginal Birth After Cesarean Labor Cervix Dilatation and Effacement Labor Pain Labor Presentation Labor Stages Uterine Contraction broad search specific search exploded

Boolean - OR DOULAS OR LABOUR SUPPORT DOULAS LABOUR SUPPORT Use to combine like terms or terms within the same concept

Boolean - AND CHILDBIRTH CONTINUOUS SUPPORT CHILDBIRTH AND CONTINUOUS SUPPORT Use to combine together different concepts

Boolean - NOT DOULA NOT MIDWIFE DOULA MIDWIFE Use to exclude terms from your search

Using Boolean in your strategy POPULATION INTERVENTION EVALUATION CHILDBIRTH OR LABOUR DOULAS OR LAY SUPPORT ATTITUDES, VIEWS, OPINIONS AND AND

x  x   

Citation searching (Web of Science feature) Find a key reference from (at least) last 5-10 years and follow all references that cite it

Other search techniques
Reference chaining: Follow up references from reference lists of relevant articles
Hand searching: Identify key journals in your field and browse them cover to cover
Relevance feedback: Look at subject indexing for a key reference and use to modify your search terms (Also “See Related Records” features)

Related records EITHER on the basis of frequency of common subject headings (MEDLINE) OR on the basis of frequency of common citations (Web of Science)

Optimal search strategies

What is an optimal search strategy?
“ optimal permutations of search terms found in the titles, abstracts or the subject indexing of relevant articles that have been demonstrated to have a high correlation with study quality”
“ pre-prepared searc h strategies, previously referred to as ‘search filters’, ‘quality filters’, ‘hedges’ or ‘optimal search strategies’… developed (and usually tested) for use with particular databases and/or search interfaces to retrieve specific types of evidence, study design or …information more effectively”

Example 1 – Qualitative Research
Qualitative Research/ OR
Questionnaires/ OR
exp Attitude/
findings OR
interview$ OR
Interviews/ OR
qualitative

Example 2 – User Views
Exp Attitude/
Attitude$ OR
(user$ adj view$) OR
opinion$

Evaluating your literature searching
Evaluation [3 mins]

Evaluating your search strategy Relevant Not Relevant Retrieved Use to generate additional search terms Eliminate terms with poor yield Not Retrieved Use reference lists from key articles to identify these No further action required

Take Home Message 3: Judge not by what you have retrieved but by what you may have missed!

And finally …
Documenting a search
Helps to avoid duplication, allows replication in future
e.g. date of search, sources searched, no. of hits, details of strategy, etc.
Reference management
Reference Manager, EndNote, etc.

Sources of help
Your local University library
Database help pages
Web-based teaching materials
Reading List

Evaluating your literature searching [10 mins]
Evaluation

Evaluation
Identify one thing that you will do when you get back to work as a result of today’s workshop
Identify one aspect of today’s workshop that you will need to explore further.

Booth 000

by richard kemp on Oct 23, 2008

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