Literature Reviews


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Literature Reviews

  1. 1. Literature Reviews Skills Talk Medical Microbiology Dr Preneshni R Naicker
  2. 2. Objectives <ul><li>What is a Literature Review? </li></ul><ul><li>Functions of a Literature Review </li></ul><ul><li>How to conduct a Literature Review </li></ul><ul><li>Writing up a Literature Review </li></ul>
  3. 3. What is a Literature Review ? <ul><li>“ Review of literature is the process of taking stock of existing knowledge in order to make informed choices about policy, practice, research direction and resource allocation” (Chalmers, 2003) </li></ul><ul><li>Also called ‘research syntheses’, ‘overviews’ or ‘secondary research’ </li></ul><ul><li>Forms part of a research protocol, thesis, grant application or research publication, but may also be a stand alone activity </li></ul><ul><li>Should not merely be a summary of previous findings, but involve a critical examination and synthesis of existing reports </li></ul><ul><li>Distinction between ‘traditional reviews’ (use informal subjective methods) and ‘systematic reviews’ (use explicit reproducible methods) </li></ul>
  4. 4. Functions of a Literature Review? <ul><li>Jusification of Future Research </li></ul><ul><li>To avoid unnecessary duplication of research </li></ul><ul><li>‘ Repeating’ research in a new context is sometimes justified </li></ul><ul><li>Show what gaps in knowledge the proposed research intends to fill </li></ul><ul><li>Putting new findings into context </li></ul><ul><li>New findings must be related to what has gone before </li></ul><ul><li>This could entail adding to or overturning established knowledge </li></ul>
  5. 5. <ul><li>3. The results of a new study must be interpreted in the light of existing knowledge </li></ul><ul><li>Making sense of research </li></ul><ul><li>Studies may have conflicting findings claiming to answer the same question </li></ul><ul><li>Literature reviews contribute to deciphering and interpreting research </li></ul>
  6. 6. <ul><li>Coping with information overload </li></ul><ul><li>Massive increase in health information available </li></ul><ul><li>Literature reviews help researchers, medical practitioners and policy-makers keep up to date with information </li></ul>
  7. 7. <ul><li>Facilitating access to relevant research </li></ul><ul><li>Access to research is often haphazard or biased </li></ul><ul><li>Studies with ‘negative’ or ‘disappointing’ results are less likely to be published </li></ul><ul><li>If they are, they are less likely than ‘positive’ studies to be published in full, in journals that are widely read, or in English </li></ul><ul><li>They are therefore less likely to be cited in reports of subsequent studies </li></ul><ul><li>Good Literature Reviews reduce bias resulting from selective reporting of research </li></ul>
  8. 8. How to conduct a Literature Review? <ul><li>Format </li></ul><ul><li>Will depend on the reason </li></ul><ul><li>Overview of a broad topic (eg studies that report on the diagnosis & management of rheumatic fever) </li></ul><ul><li>Focused synthesis (eg the most reliable evidence on the effect of BCG vaccine in preventing TB) </li></ul><ul><li>Traditional approach used subjective & opportunistic methods in synthesising research – biased, leading to false conclusions </li></ul>
  9. 9. Shortcomings of a Traditional Review <ul><li>Systematic error(bias) from: </li></ul><ul><li>Incomplete literature searches eg. Only english language studies in one electronic database such as Medline </li></ul><ul><li>Selective inclusion of studies eg. Only those with findings that confirm what the reviewer has found in his/her study </li></ul><ul><li>Insufficient attention given to study quality eg. Use of inappropriate study designs or studies with flawed methods </li></ul><ul><li>Random Error (play of chance): </li></ul><ul><li>Insufficient attention given to sample size </li></ul>
  10. 10. What is a Systematic Review? <ul><li>DEFINITION (Moher et al, 1999) </li></ul><ul><li>‘ A review in which bias has been reduced by the systematic identification, appraisal, synthesis, and, if relevant, statistical aggregation of all relevant studies on a specific topic according to a predetermined and explicit method’ </li></ul>
  11. 11. Steps: <ul><li>State the objectives of the synthesis </li></ul><ul><li>Define eligibility criteria for studies to be included </li></ul><ul><li>Identify (all) potentially eligible studies </li></ul><ul><li>Apply eligibility criteria </li></ul><ul><li>Assess study quality </li></ul><ul><li>Assemble the most complete dataset feasible </li></ul><ul><li>Analyse </li></ul><ul><li>Prepare a structured report </li></ul>
  12. 12. Practically…. <ul><li>What question(s) will my review address? </li></ul><ul><li>Formulating a proper review Q is the most important step </li></ul><ul><li>What criteria will I use to determine study eligibility? </li></ul><ul><li>Determine what types of studies are to be included </li></ul><ul><li>How will I identify relevant studies? </li></ul><ul><li>List potential sources of literature eg MEDLINE </li></ul>
  13. 13. <ul><li>How will I appraise included studies for validity? </li></ul><ul><li>Publication in high impact peer reviewed journals is doesn’t guarantee validity of research findings </li></ul><ul><li>Aim to critically evaluate validity of research findings </li></ul><ul><li>How will I synthesise the study findings? </li></ul><ul><li>Provide an overall summary of the findings of primary studies </li></ul><ul><li>By means of a descriptive (narrative) synthesis or meta-analysis (formal statistical technique) </li></ul>
  14. 14. Writing up the literature review <ul><li>Determine the citation style required by the university or journal (Harvard vs Vancouver) before embarking on the review </li></ul><ul><li>Communicate clearly the </li></ul><ul><li>AIMS </li></ul><ul><li>METHODS </li></ul><ul><li>RESULTS </li></ul><ul><li>IMPLICATIONS </li></ul><ul><li>Avoid Plagiarism </li></ul><ul><li>************************************************ </li></ul>
  15. 15. Thank you <ul><li>Reference </li></ul><ul><li>Joubert G, Ehrlich R (eds). Epidemiology: A Research Manual for South Africa. 2 nd ed:66-76. Oxford University Press </li></ul>