In order to put your research into context it is important to briefly describe what others have written on your topic. A literature review surveys scholarly articles, books and other sources (e.g. dissertations, conference proceedings) relevant to a particular issue, area of research, or theory, providing a description, summary, and critical evaluation of each work. The purpose is to offer an overview of significant literature published on a topic.
A literature review requires several stages (from University of California, Santa Cruz
• Problem formulation – which topic or field is being examined and what are its component issues?
• Literature search – finding materials relevant to the subject being explored
• Data evaluation – determining which literature makes a significant contribution to the understanding of the topic
• Analysis and interpretation – discussing the findings and conclusions of pertinent literature
Literature reviews should comprise the following elements:
• An overview of the subject, issue or theory under consideration, along with the objectives of the literature review
• Division of works under review into categories (e.g. those in support of a particular position, those against, and those offering alternative theses entirely)
• Explanation of how each work is similar to and how it varies from the others
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research
In assessing each piece, consider:
• Provenance – What are the author's credentials? Are the author's arguments supported by evidence (e.g. primary historical material, case studies, narratives, statistics, recent scientific findings)?
• Objectivity – Is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness – Which of the author's theses are most/least convincing?
• Value – Are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?Identifying and evaluating types of research
Critical appraisal is the process of carefully and systematically examining research to judge its trustworthiness, and its value and relevance in a particular context.What is a Systematic Review?
(from Critical Appraisal Skills Programme (CASP))
Frequently there will have been more than one study addressing a particular health question. In such circumstances it is logical to collect all these studies together and base conclusions on the cumulated results. However the same scientific principles as would be expected in the original studies need to be applied to the identification, sorting and analysis of potentially relevant studies. This is what is meant by a systematic review. The most obvious sign that a review is systematic will be the presence of a methods section. Meta-analysis is the statistical process of combining the results from several studies that is often part of a systematic review.CASP Systematic Review ChecklistWhat is a Randomised Controlled Trial (RCT)?
An RCT is a type of interventional or experimental study design. Participants (individuals or groups) are randomly allocated to receive either the new intervention being tested or a control treatment (usually the standard treatment or a placebo). Each arm of the study is then followed up and the amount or severity of the disease measured in the intervention group and compared with the control group. RCTs are by definition prospective.CASP Randomised Controlled Trial ChecklistWhat is a Qualitative study?
A qualitative study examines the experiences and beliefs of people from their own perspective. It can take many forms including in-depth interviews and focus-groups with analysis attempting to identify underlying themes. Verbatim quotes of participants can be used to illustrate these themes.CASP Qualitative ChecklistWhat is a Cohort study?
A cohort study, also known as a follow-up or longitudinal study, is another observational study design. In this study a population who do not have the health outcome or disease of interest are first divided into those who are exposed to a risk factor and those who are not. Alternatively exposed and unexposed populations may be chosen separately. Irrespective, both groups are then followed, often over long periods of time. At the end of the period of observation the incidence of disease or frequency of health outcome in the exposed group is compared to that in the unexposed group. The study is generally prospective as it looks forward from potential cause to consequence.CASP Cohort Study ChecklistWhat is a Case-Control study?
A case-control study belongs to the observational group of studies. It begins by choosing individuals who have a health outcome or disease whose cause you want to investigate. These are the cases. Controls without the health outcome are then chosen. You then determine the proportion of cases who were exposed to any risk factor of interest in the past, and compare this with the proportion exposed in the control group. The study is generally retrospective because it looks backwards in time to the earlier exposures of individuals.CASP Case Control ChecklistOther research checklists
• CASP Clinical Prediction Rule Checklist
• CASP Diagnostic Checklist
• CASP Economic Evaluation ChecklistOther critical appraisal resources
The CARS Checklist for Research Source Evaluation
by Robert Harris, 2015
Few information sources will meet every criterion in the list, and even those that do may not possess the highest level of quality possible. But if you learn to use the criteria in this list, you will be much more likely to separate the high quality information from the poor quality information.
• Credibility trustworthy source, author’s credentials, evidence of quality control, known or respected authority, organizational support.
Goal: an authoritative source, a source that supplies some good evidence that allows you to trust it.
• Accuracy up to date, factual, detailed, exact, comprehensive, audience and purpose reflect intentions of completeness and accuracy.
Goal: a source that is correct today (not yesterday), a source that gives the whole truth.
• Reasonableness fair, balanced, objective, reasoned, no conflict of interest, absence of fallacies or slanted tone.
Goal: a source that engages the subject thoughtfully and reasonably, concerned with the truth.
• Support listed sources, contact information, available corroboration, claims supported, documentation supplied.
Goal: a source that provides convincing evidence for the claims made, a source you can triangulate (find at least two other sources that support it).