LITERATURE REVIEWS

What is a literature review?  “a synthesis of the literature on a topic.”  (Cottrell & McKenzie, 2011, pg 40)

Why do a literature review?  Justify need for study  Establish a historical perspective, context  Refine the research question  Identify appropriate theory, methodology, and instrumentation

SOURCES  Primary sources  Written by the person or persons who actually conducted the research  Secondary sources  Report on or summarize primary sources

Electronic data bases  Descriptors, key terms  MeSH terms ( Medical Subject Headings)  The National Library of Medicine controlled vocabulary thesaurus used for indexing articles for MEDLINE  ahl_mesh/cinahl_mesh.html ahl_mesh/cinahl_mesh.html

Electronic Data Bases Index Medicus PsychLIT Dissertation Abstracts Social Science Index ERIC PsychINFO ISI Web of Science CINAHL PubMed/MEDLINE

Boolean Operators  ooltips.aspx ooltips.aspx  AND  OR  NOT  Nesting using parentheses, establishing order  Truncation using wildcards

Full-Text Articles The only way to truly understand a study is to read the full text of the article. How to acquire full text articles:  Library websites (e-journals) and physical collections  Journal websites / Internet searches  Request an “interlibrary loan” from a university library  the author and request an electronic copy

Steps for Reading Articles 1. Re-read the abstract 2. Look carefully at the tables and figures for important results 3. Read the entire text of the article  Take notes about which exposures, diseases, and populations the study examined – and how they might relate to a new research project 4. Review of the reference lists for related papers

What Makes Research Original? Originality requires one substantive difference from previous work:  a new exposure of interest  a new disease of interest  a new source population  a new time period under study  a new perspective on a field of exploration

What Makes Research Original? Example: A literature review finds several studies that have shown that older adults (the population) who take 30-minute walks several times a week (the exposure) score higher on memory tests (the disease or outcome) than adults who do not routinely walk for exercise. A proposed new study could examine…

What Makes Research Original?  Is playing table tennis (a new exposure) equally effective at improving memory in older adults (the same disease and population)?  Do older adults who walk several times a week (the same exposure and population) improve their balance (a new disease or outcome)?  Does walking improves memory (the same exposure and disease) in children (a new population)?

What Makes Research Original?  The real challenge in reviewing the literature and selecting a study question is not finding a previously unexplored topic.  The main challenge is to limit the research project to one solid idea out of the many possibilities.  The aim of a research project is usually to find and address gaps in the literature (missing pieces of information that a new study could fill) and to build on previous work.

Benefits  A literature review is an effective way to become an expert in the literature on a well-defined topic  A literature review is a helpful step in preparing for future primary or secondary analyses  Review articles are often cited more often than reports of individual field studies

Limitations  Not all journals publish review articles (especially reviews that the editors do not solicit)  Reviews are sometimes perceived to be a less rigorous form of research than projects that collect new data and/or involve statistical analysis

Selecting a Topic  The most important decision is to select a topic that is narrow enough that all the relevant publications can be acquired.  The topic may need to be modified after a preliminary search, depending on the number of articles available.  8 = too few  expand the scope  352 = too many  narrow the scope

Primary, Secondary, and Tertiary Research