literature reviewliterature review •a literature review is an objective, critical summary of...

Literature Review

PST 426 – Research Methodology and Biostatistics

Miss Adebayo O.E

PST 426 - Research Methodology and Biostatistics 1

Literature review

• A literature review is an objective, critical summary of published research literature relevant to a topic under consideration for research.

• Its purpose is to create familiarity with current thinking and research on a particular topic, and may justify future research into a previously overlooked or understudied area.

• A literature review compiles and evaluates the research available on a certain topic or issue


Literature review

• A literature review is simply a summary of what is known about a particular topic.

• It is concerned about what has been written on a particular subject so as to serve as a prelude to further research

• A literature review should focus only on the relevant academic literature: popular or non-academic sources may be brought in occasionally to illustrate a point, but the central interest is always on the data collected or the theories put together by recognised experts in the field.


Literature review

What is involved in writing a literature review?

• Research – to discover what has been written about the topic

• Critical Appraisal – to evaluate the literature, determine the relationship between the sources and ascertain what has been done already and what still needs to be done

• Writing – to explain what has been found


Purpose of the Literature Review

• To provide background information about a research topic. • To establish the importance of a topic and justify need for a study. • To demonstrate familiarity with a topic/problem. • To set the stage for further work• To prevent unnecessary duplication of work and time wastage Literature review can inspire new research ideas Help lay foundation for studies To shape research questions To discover appropriate research methods and approaches Point to conceptual/theoretical framework


Qualities of a Good Literature Review

An effective literature review should :

• Be organized around and directly related to the research

• Synthesize results into a summary of what is and is not known.

• Identify areas of controversy in the literature.

• Formulate questions that need further research

• Must be comprehensive, thorough & incorporate up-to-date references.

• Must be systematic.

• Must be reproducible.

• Must show balance and absence of bias


Steps to writing a literature review

• Identify the topic/research question

• Searching for reliable, accurate and up-to-date material on the topic

• Synthesising the key ideas, theories and concepts into a summary of what is known

• Evaluation of and discussion on these ideas, theories and concepts

• Identifying particular areas of debate or controversy

• Preparing the ground for the application of these ideas to new research


Searching for material

When searching for or choosing material, the following questions need to be asked• What is the specific topic of interest?, What kind of material do is needed?• What type of literature is available (e.g., journals, books, government

documents)?• What kind of literature is particularly authoritative in this academic

discipline?• Is the search wide enough to ensure all relevant materials has been

identified?• Is the search narrow enough to exclude irrelevant material?• Consideration of as many alternative points of view as possible?• Will the reader find the literature review relevant, appropriate, and useful?


Sources of Information/Literature• Textbooks, modules, etc

• Research surveys, reports and regulatory and policy documents produced by government & non-governmental agencies

• Review articles, original articles in journals.

• Guidelines for best practice, clinical protocols, professional standards and reviews

• Dissertation and theses

• Conference proceedings

• Library holdings: accessed through online catalog

• Bibliography data bases.


Types of Literature

• Primary source research: descriptions of studies by researchers who conducted them. (journal original articles, theses, dissertations, conference abstracts and proceedings )

• Secondary source research: Description of studies prepared by someone beside the original researcher=. (e.g. book chapters & journal articles that review literature)

• Opinion articles, case reports and clinical anecdotes have limited utility in literature review because they are subjective in nature and does not state the current state of evidence on the research question.


Search Strategy

• Search for relevant articles should begin from Bibliographic databases

• Internet sources such as google or bing should be considered as supplements not alternatives to a search of bibliographic databases.

• In searching bibliographic databases, one of the following strategies can be used:

• Ancestry approach (footnote chasing)

• Descendancy approach


Search Strategy

Ancestry approach (footnote chasing)

• Using citations from relevant studies to track down earlier research on which the studies are based (the ancestors)

Descendancy approach

• Finding a pivotal early study and to search forward in citation indexes to find more recent studies (descendants) that cited the key study.


Electronic Bibliographic Databases

• MEDLINE(Medical Literature On-Line)• CINAHL (Cumulative Index of Nursing and Allied Health Literature).• AMED (Allied and Complimentary Medicine)• Cochrane Library –http://www.cochranelibrary.com• PEDro-Physiotherapy Evidence Database- http://www.pedro.org.au/• SportDiscus• DARE (Database of Abstracts of Reviews of Effects)• ASSIA (Applied Social Sciences Indexes and Abstracts)• Science Citation Index• EMBASE (Excerpta Medica database)


Searching Bibliographic Databases

• The keyword to launch the search should be identified

• Keyword is a word or phrase that captures the key concepts in the research question.

• For quantitative studies, the keywords to begin with are usually the primary independent variables and dependent variable then population.

• For qualitative studies, keywords are the central phenomenon of interest plus the population

• Indexing in databases have specific subject headings (subject codes).

• Entering keyword into the search field will make program to institute both subject search and text-word search.


Searching bibliographic databases

• Another way is to search by author especially established expert in a field (e.g John AE or John[au])

• Multiple words having the same root can also be searched using wildcard characters like “$” or “*” depending on the database and search program. The wildcard character is inserted after the truncated root e.g. nurs*

• Boolean operators “AND” or “OR” or “NOT” can be used to restrict or expand the search. (Blood pressure “AND” Exercise vs Blood pressure “OR” Exercise). Boolean operators must be entered in uppercase.



• Identify synonyms for each concept

• Construct logical relationships among the concepts using “AND”, “OR”, and “NOT”.

• Search can be limited according to certain filters offered by the database e.g.• Language.

• year of publication”

• Abstract or full text

• Free text

• Human or animal studies



• The topic should be focused on: A literature review aims to cover all of the research on a given topic.

• If the topic is too large, there will be too much material to cover it adequately.

• Materials should be read with a purpose of isolating key themes or issues related to the own research interests.


Evaluating and screening sourcesLiterature should be screened for:

• Accessibility

• Relevance

• Methodologic quality

For each material, the following should be considered:

• Credentials: Is the author an expert?

• Argument/Evidence: Does the evidence support the conclusion? Is the argument or evidence complete?


Evaluating and screening sources

When comparing sources, consider:

• Conclusions: Does all research arrive at the same conclusion or are there differing opinions? What evidence or reasoning are the differences based on?

• Gaps or omissions: What questions are raised by the literature?


Evaluating and screening sources

• The researcher should skim through the books and articles identified as potentially relevant. The chapter summaries, abstract can serve help to determine the relevance of the material to the research.

• After the relevant materials have been chosen, the researcher reads the material carefully to determine the key point discussed, research methods, the strength and limitations of the study, the contribution of the work to the proposed research e.t.c


Writing the literature review

• The literature review should be built around the key topic. It should show how each piece of literature contributes to, or challenges, the central theme.

• It should have a beginning, middle and end. In other words, you need to guide

• The literature review should be written after careful reading, note-taking and planning

• Unsubstantiated claims should not be made, writing must be backed with evidence

• The materials should be summarised as much as possible in the researchers own words


Writing the literature review

• The writer/researcher should be selective in the number of points drawn out from each piece of literature;

• Exaggerated generalizations should be avoided

• Personal opinions should be backed by clear arguments

• The write –up should be revised and edited as much as possible. It should also be checked for fluency, structure, evidence and referencing.

• Grammar and spelling is very important


Components of a literature review

Introduction

• A concise definition of a topic under consideration, as well as the scope of the related literature being investigated.

• The introduction is states the general findings of the review (what do most of the sources conclude), and comment on the availability of sources in the subject area.

• Writer’s reason for reviewing the literature



Main Body

• The main body could be organized in different ways (e.g thematically or chronologically)

• Each work should be critically summarized and evaluated for its premise, methodology, and conclusion.

• The accuracy, depth, and relevance of each work should be identified as well as the inconsistencies, omissions, and errors



Conclusion

• The conclusion summarizes the key findings of the review in general terms. Notable commonalities between works, whether favourable or not, may be included here.

• Major methodological flaws or gaps in the research, inconsistencies in theory and findings and areas or issue pertinent to future study should be pointed out

References

• A literature review must contain complete and correct citations for every source As well as accurate in-text citations


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