How to critique a Research Literature Review

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The NIHR Research Design Service for Yorkshire & the Humber How to Search and Critically Evaluate Research Literature Author Michael Hewitt Revised by Christine Keen This Resource Pack is one of a series produced by The NIHR RDS for the East Midlands / The NIHR RDS for Yorkshire and the Humber. This series has been funded by The NIHR RDS EM / YH. This Resource Pack may be freely photocopied and distributed for the benefit of researchers. However it is the copyright of The NIHR RDS EM / YH and the authors and as such, no part of the content may be altered without the prior permission in writing, of the Copyright owner. Reference as: Hewitt M., How to Search and Critically Evaluate Research Literature. The NIHR RDS for the East Midlands / Yorkshire & the Humber, 2007 Michael Hewitt Evaluation, Audit and Research Manager, Sherwood Forest Hospitals NHS Trust Last updated: 2009 The NIHR RDS for the East Midlands Division of Primary Care, Leicester: th 14 Floor, Tower building University of Nottingham Nottingham: University Park Nottingham NG7 2RD Tel: 0115 823 0500 The NIHR RDS for Yorkshire & the Humber ScHARR Sheffield: The University of Sheffield Leeds: Regent Court York: 30 Regent Street Sheffield S1 4DA Tel: 0114 222 0828 © Copyright of The NIHR RDS EM / YH (2009) The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 1 Literature Searching Table of Contents Page 1. Introduction……………………………………………………… 4 2. The Research Process......................................................... 6 3. Research literature……........................................................ 11 4. Using databases to locate published research…………... 14 5. Planning and conducting a literature search……………... 18 6. Examining the results and writing a review………………. 23 7. Answers to exercises…………………………………………. 34 8. References……………………………………………………… 37 9. Further reading and resources…….................................... 37 10. Glossary…………………………………………………………. 38 The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 1 Literature Searching 1. Introduction The amount of health care research undertaken has grown enormously over the past two decades. More research is being done by more people in almost every professional group. This is due to a number of factors. They include: • more health care staff undertaking research as part of academic studies • increased funding for research • pressure on academics in university health care faculties to undertake original research that can be written for publication. At the same time, health care professionals are being encouraged to base their clinical practice on research based knowledge. Every year, hundreds of professional journals are published containing thousands of reports of research studies. The health care professional searching the literature for information on, for example, factors affecting patient uptake of screening services, is likely to reveal a bewildering number of research reports from a growing array of sources. The reports will vary in terms of quality, comprehensibility and relevance to practice. Surprising as it may seem, it is an unfortunate fact that not all published research is good quality. Many more studies, while being basically well researched studies, will have limitations due to aspects of research design. The technique of the literature review is to try to make all of the above more manageable. The process of carrying out a literature review can be described by two main activities. These are searching and then critically evaluating research literature. In addition, the process and findings should be written-up as a complete record. These activities are outlined below and covered in later sections in more detail. Searching the literature is a research method in its own right. The method uses specific technical terms and there are guidelines to follow that are designed to seek out the literature that is relevant to the defined area of study. The literature identified from the search should then be critically evaluated. The purpose of critical evaluation is to enable the practitioner to read research studies objectively: to identify the good points and bad points, the strengths and weaknesses, the usefulness of a report and the limitations. Additionally, critical reading of research reports increases the practitioner's understanding of the research process. Lastly, practitioners undertaking research of their own will benefit from developing their critical evaluation skills. It will assist them to appraise their own research projects and enhance their skills at all stages of the research process from project design to writing the final report. This resource pack provides guidelines on how to both search for and then critically appraise research reports. It is intended for use by health care professionals with little or no previous research knowledge. Readers will be guided through the processes and provided with information on the factors that can affect the quality of the literature search and the research articles found. This will be supported by examples from health services research. Exercises will be used to reinforce the reader's understanding of the text. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 2 Literature Searching LEARNING OBJECTIVES The aim of this pack is to provide an introduction to searching and evaluating research literature. After working through the pack you will be able to: • Appreciate the role of the literature review in the research process • Conduct a literature search • Follow the sequence of a written research report. • Systematically consider each section of a research report identifying strengths and weaknesses that may be present. • Critically appraise the overall value of a research report and consider whether or not to apply future research findings to practice. • Write a brief and well-structured literature review. This pack defines some key terminology and presents an overview of the process of literature searching and critical evaluation. 1.2 Summary This section has presented an overview of searching and evaluating the literature. The following sections look in more detail at the process. Sections 2 and 3 examine the publication of health care research. They describe in more detail what is meant by the literature and how a piece of research becomes a part of this body of knowledge. Section 4 describes the methods that have been devised for selecting out particular subsets of the literature, and section 5 includes a step-by-step approach to planning and conducting a literature search. Section 6 provides guidance on how to process the results of your literature search, critically evaluate the research articles found and presents brief guidelines on how to write a literature review. To assist the learning process practical exercises are provided at the key stages of the pack. These take you through the essential steps of conducting your own review. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 3 Literature Searching 2. The Research Process Thousands of books and articles have been written about research. It is an enormous topic and no one knows everything there is to know about it. But in order to search and read research literature critically, it is essential that the reader has a basic understanding. Research is conducted in a systematic way. The process of research is made up of a number of stages, which the researcher must proceed through, for the research project to be completed satisfactorily. The main stages are presented in Figure 2.1 and are described in brief in this section. If you have no previous awareness of research at all you may find it useful to read The NIHR RDS EM / YH Resource Pack An Introduction to the Research Process, which provides more information about each stage in the process. Identify research problem Literature review Methodology Plan research Access and ethical Figure 2.1 The Research Process considerations Carry out research Pilot study Data collection Data analysis Conclusions The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 4 Literature Searching When deciding to carry out a research study the researcher starts out with an idea for which a plan of investigation is developed. In developing the plan the researcher takes into consideration things such as: • what am I trying to find out? • what sort of information do I need? • what is the best way to collect the information? • where can I get the information? • how many people will I need to ask? • how will I analyse and make sense of the information I collect? Once the information has been collected and analysed the researcher has a responsibility to disseminate a report of the project. This includes: • explaining how the research was conducted • reporting the results • highlighting the limitations of the research • drawing out main conclusions • identifying possible recommendations for practice and for further research. The research process is the sequence of events that the researcher goes through in developing and disseminating the research project. Different textbooks list the sequence of events in slightly varying ways but they are essentially similar to the list shown in Figure 2.1. The remainder of this section provides a concise summary of each stage. 2.1 Identification of the Research Problem Every research project starts with an idea; something that the researcher is interested in knowing more about or is worried about; something that is perceived as a problem or as a knowledge gap that needs to be filled. At the outset, the research idea is often vague or too broad to be covered in one research project. It needs to be refined to make it manageable and researchable. The researcher needs to think the idea through and the thinking process is informed by the next stage. 2.2 Review of the Literature Before embarking on a research project the researcher should search and review existing literature. The process of searching and evaluating research literature is detailed in subsequent sections of this resource pack. However, it is useful at this stage to provide descriptions of some key concepts. What is a literature review? A literature review is a self-contained piece of written work that gives a concise summary of previous findings in an area of the research literature. It reflects an author’s knowledge and interpretation of the area of interest. It has a reference section that lists The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 5 Literature Searching the individual pieces of work referred to in the review. Like all pieces of written research output it should include a description of the methods used to create the work. Literature reviews vary considerably in their depth and breadth, as well as style of presentation, depending on the purpose intended by the author. This may range from a superficial search of the literature to give a researcher an insight to an area of potential research through to a scientifically rigorous ‘systematic review’. Researchers committed to writing a review, however, should be encouraged to go beyond superficial searches and simply listing research works; they will inevitably get a biased or incomplete view of the research area under investigation. Instead, they should develop skills that will enable them to systematically search for literature and critically review the research uncovered by the search. This pack aims to help health care professionals achieve these skills. Why do a literature review? A preliminary review of the literature will help in further identifying and clarifying your research problem. A little further down the line it may provide the theoretical input to your research idea and help in the formulation of the research question. More specifically, a literature review will: 1. provide an up-to-date picture of the research area of interest and show which areas have been investigated and the results obtained 2. identify methods of investigation that could be used in further research 3. give indications of problems that might be encountered and possible solutions 4. reveal common findings among studies 5. reveal inconsistencies between studies 6. identify factors not previously considered 7. provide suggestions for further research. In summary, completion of the literature review enables the researcher to revisit the original research idea and define the exact focus of the research problem. Published literature reviews Examples of published literature reviews include: Chalmers and Pearson (2005) on oral hygiene care for residents with dementia; Richardson et al. (2005) on indoor environment and asthma; and Lui et al. (2005) on effective problem-solving interventions for caregivers of patients with stroke. 2.3 Research Methodology The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 6 Literature Searching Methodology Methodology refers to matters regarding the structure and design of the research study. It deals with such issues as: the type of information required; the research design; the method of collecting data; and the source of information, which is known as the sample. Type of information This depends on the original research idea. If the researcher wants to collect measurable information about a topic this is referred to as quantitative research. It looks at how big a problem is, how many people are affected by it, how often something occurs, whether one thing is more or less important than another. If the researcher is trying to understand something in more detail or to describe a situation so that people can understand it better, this is usually qualitative research. In qualitative research, attention is focused on answering questions such as why? in what way? what are the implications? Rather than, how many? how often? how much? as occurs in quantitative research. The research design This refers to the type of research. There are many different types of research design. Research can be carried out using experiments, surveys, case studies, action research, ethnography, grounded theory, and phenomenology. The glossary in Section 2 contains a concise definition of each of these research designs. The method of collecting data The most commonly used methods of collecting information are interviews, questionnaires and observation. Interviews are usually conducted on a one-to-one basis but some studies may use group interviews or focus groups. Interviews can be highly structured, semi-structured or unstructured. The degree of structure affects the flexibility of the interview. Questionnaires comprise a written set of questions, which are answered by all respondents in a study. Observation is a technique for collecting data through visual observation of events. It requires the nature of the data to be observable. The sample In any research the researcher has to identify the population under study. If a School Nurse wants to carry out research about school children she needs to decide if this means any school child or is she interested in a particular section of the school population. Furthermore, if she eventually decided that the research was actually about, for example, "poor attendees" a criterion standard for poor attendance should be identified. If the target population is large it may not be feasible to include everyone in the research so a sample has to be selected. There are different ways of sampling such as random sampling, convenience sampling, purposive and cluster sampling. Brief definitions of these are included in the glossary at the back of the pack. There are reasons to use different approaches to sampling and each approach has strengths and weaknesses. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 7 Literature Searching 2.4 Access and Ethical Considerations In trying to access the sample the researcher has to consider how this can practically be achieved and whether any permission must be sought. Access to patients normally requires permission from the responsible medical officer or the NHS organisation. Access to staff requires permission from their manager. When seeking permission the researcher can usually secure practical help and advice in accessing subjects. The researcher must also consider any ethical implications of the research. At the very least this involves issues of confidentiality and anonymity but there may be other factors to consider which unless resolved could potentially have negative implications for the subjects directly or indirectly. The researcher should seek formal permission to undertake the study from the local research ethics committee. 2.5 Pilot Study Once the researcher is ready to undertake the study he should carry out a small pilot study to check that the methodology has been correctly thought through. The pilot is the study in miniature and gives the researcher an opportunity to identify any problems and to modify the research method before embarking on the main study. 2.6 Data Collection At last the researcher reaches the stage of conducting the interviews, sending out the questionnaires or recording observations. 2.7 Data Analysis The researcher reviews the data that has been collected and systematically analyses the responses of subjects. Data are described, summarised and, if quantitative in nature, statistically analysed in order to produce the results of the study. 2.8 Conclusions The researcher reviews the results and identifies the main conclusions. Crucially it is important to return to the original research question to see whether it has been answered. Ways in which the results could be considered for application to practice are recommended, as are areas where further research is needed. An important part of this stage is recognition of the limitations of the study so that readers who may consider acting on the results of the study can take them into consideration. 2.9 Summary This section presents an overview of the research process and places the literature review within this context. The next section looks at how the research literature is developed. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 8 Literature Searching 3. Research Literature This section takes the reader through the notion of the ‘research literature’ in further detail; it describes how research is published and how it is made accessible to researchers and practitioners. 3.1 What is meant by the ‘Literature’? In professional and academic disciplines the term ‘literature’ is used to describe all the published work on a particular subject. Within this definition, no judgement is made regarding the quality of any single piece of work. The main body of the literature lies within academic and professional journals. It has been estimated that over 20,000 journals published each year carry articles that are relevant to the disciplines of the medical and health sciences. In addition to journal articles, research is also published in books, reports, conference proceedings, theses and dissertations. The different elements of the research literature are described below. Journals The result of the research process (Figure 2.1, Page 6) is a document that needs to be made accessible to the relevant research community. This is necessary for two main reasons. First, so that the findings are open to critical examination by others, and second, that they are accessible to all who might benefit from them. The traditional vehicle for publishing research findings is journals; traditionally these are magazine- sized publications containing articles but increasingly they are being published in electronic form for access via the world wide web. Journals are published in issues at regular intervals usually weekly, monthly or quarterly. Because of the regularity of publication they are also known as periodicals or serials. This regularity means that each new issue contains articles that describe the latest research findings; this is a distinct advantage over other publication media such as books that take longer to produce and update. The publication of an article in a journal involves a number of steps: 1. Writing the article: this requires the author or authors to present their research findings in a broadly scientific style. The layout of the article may also need to conform to a particular style laid down by the editorial board of the journal; this may require the authors to include a summary (or abstract) of their work, or to keep within a specified word limit for example. 2. Submission of the article to a journal: usually via the journal’s editor. 3. Refereeing: some journals require articles to be critically reviewed by experts in the field prior to publication. This process is also known as ‘peer-review’. Referees may suggest amendments to the original text before publication can proceed, or may reject the article outright if they argue the work is fatally flawed in some way. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 9 Literature Searching 4. Changes to the original text: if indicated by the referees. 5. Publication: if, or when, the editor accepts the article. There are basically two main types of journal: • Research journals • Professional journals. Research journals publish peer-reviewed articles. A few examples of the many thousands of research journals available include the British Medical Journal, the Lancet and the British Journal of General Practice. In contrast, professional journals publish articles on professional issues, service developments, the use of research findings in practice and some short research articles. They are primarily written for practising health care professionals rather than researchers. Examples include the Health Visitor Journal, the Journal of Community Nursing and Practice Nurse. Reports Research reports appear in many different shapes and sizes. In general, however, they will give a more detailed account of a piece of research than that found in a journal article. Reports of original research may arise from many different sources including health authorities, professional organisations and pharmaceutical companies. The publicity and distribution of some reports may be very limited making it difficult to know of them or obtain copies. Theses and dissertations Theses and dissertations are very detailed and comprehensive accounts of research work. They are usually submitted for a higher degree at a university. Like reports their publicity and distribution may be very limited. Conference proceedings Conference proceedings comprise brief summaries of research work presented at conferences. A more detailed and complete account of the work may appear at a later date in a journal article, report or thesis. Researchers often use conferences to present preliminary findings of their work. Books Textbooks generally provide comprehensive overviews of a particular subject. In doing so they may refer to, sometimes extensively, the research literature found in journal articles, reports, conference proceedings or theses. They are not usually used to present new research findings. There are, however, a few exceptions to this and some very important and influential research findings have been published in book format. These are sometimes known as research monographs. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 10 Literature Searching 3.2 Summary Health care research is published in a variety of formats including journal articles, books, reports, conference proceedings, theses and dissertations. The first stage of the literature review is to locate all the research findings on a particular subject from the literature, regardless of the publication format. The next section shows how this can be achieved. Exercise 1 The publication process Locate one or two journals that present articles written by health care professionals or researchers. Look for information on the publication of articles within each journal (this may be presented as instructions for authors or may be found with the general information about the journal or editors located on the front inside cover). Use the information to answer the following questions: • Is there a limit to the number of words each article must not exceed? • Are the articles peer-reviewed? • Should each article include an abstract? • How should references be presented? • Can the article be submitted to the journal’s editor electronically? Relevant literature List any journals you know of that are likely to contain articles relevant to your profession. Add to the list any relevant reports, theses, conference proceedings and books that you know of. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 11 Literature Searching 4. Using Databases to Locate Published Research A key stage in the literature review is to search out all the research literature on a particular subject. This may at first seem an impossible task given the huge volume of research literature published worldwide. This problem, however, has long been recognised and considerable effort has been made to simplify and speed up the process. The results of this effort are available through on-line, web-based databases, also known as bibliographic databases. These offer facilities for searching for published research. In this respect they differ from other web-based search engines like Google that offer access to huge amounts of information but do not necessarily find research articles that have had some degree of quality control. This section describes the main bibliographic databases used to locate published research and how to use them. The databases give references to journal articles and conference papers, giving you the bibliographic details of each published paper e.g. author(s), article title, journal title, volume and year, and often include an abstract or summary of contents. 4.1 Bibliographic Databases At the time of writing the NHS has an agreement with the suppliers of a number of databases such that these resources are available to all NHS staff. Similar arrangements are made for staff employed by universities. The databases are available either through the service provider ‘Athens’ ( or through the National Library for Health ( A username name and a password are required and your local NHS or university library should be able to provide these. NHS staff can access the following databases: • Medline • Cinahl • Psycinfo • Embase • AMED (Allied and Complementary Medicine) • British Nursing Index • DH-Data • King’s Fund. A brief description of these databases is provided in Table 4.1 below. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 12 Literature Searching Table 4.1 Key features of the Main Bibliographic Databases Database Subject coverage Types of Years Name sources covered covered MEDLINE Medline covers the whole field of medicine including dentistry, veterinary Journal articles 1950 - medicine and medical psychology, clinical medicine, anatomy, pharmacology, toxicology, genetics, microbiology, pathology, environmental health, occupational medicine, psychology, biomedical technology, health planning and administration, space life science, and many other related subject areas. CINAHL Cinahl covers all aspects of nursing and allied health disciplines. Seventeen Journal articles, 1982 - allied health disciplines are covered: cardiopulmonary technology, dental pamphlets, pamphlet hygiene, emergency services, medical/laboratory technology, medical chapters, books, (Cumulative Index assisting, athletic training, occupational therapy, optometry, physical therapy book chapters, to Nursing and and rehabilitation, the physician's assistant, radiological technology, masters theses & Allied Health respiratory therapy, social service in health care, speech-language dissertations. Literature) pathology, nutrition and dietetics, audiology and surgical technology. Journals from biomedicine, alternative therapy, health sciences, librarianship, health promotion/education, and consumer health are also scanned for relevant articles. PsycINFO Psychology practice and research and psychological aspects of related Journal articles, book 1806 - clinical disciplines including medicine, psychiatry, nursing and chapters, (Psychological pharmacology, drug and behavioural therapy, treatment of disease, drug dissertations Abstracts) addiction, developmental psychology, and educational psychology, as well as the psychological aspects of such areas as linguistics, social processes, pharmacology, physiology, nursing, education, anthropology, business and law. EMBASE EMBASE covers the whole world's biomedical literature whilst concentrating Journal articles 1974 - in particular on European sources. The emphasis of the database is on the pharmacological effects of drugs and chemicals. Over 40% of current data is drug-related. Other subjects: human medicine and biological sciences relevant to human medicine, health affairs (occupational and environmental health, health economics, policy and management), drug and alcohol dependence, psychiatry, forensic science, pollution control, biotechnology, medical devices and alternative medicine. AMED Complementary or alternative medicine: acupuncture, herbalism, Journal articles, 1985 - reflexology, homeopathy, holistic treatment, iridology, hypnosis, traditional newspapers and (Allied and Chinese medicine, moxibustion, chiropractic, occupational therapy, books Complementary meditation, osteopathy, physiotherapy, yoga, psychotherapy, rehabilitation, Medicine) healing, research, diet therapy, ayurvedic medicine, Alexander technique. BNI Nursing and midwifery plus medical, health management and allied health Journal articles 1994 - fields relevant to UK nurses and midwives. Covers mostly UK nursing and (British Nursing midwifery journals although a representative number of non-UK specialist Index) journals are also covered. Examples of subject areas covered: accident & emergency nursing, breast cancer, evidence based practice, learning disabilities, midwifery, nurse practitioner, orthopaedic nursing, perinatal & neonatal mortality, psychiatric nursing, reflective practice, student nurses, theatre nursing, wounds. DH-DATA Health Core subjects: health service and hospital administration, with an emphasis Journal articles, 1983 - Administration and on the British National Health Service, including planning, design, books, reports, Medical Toxicology construction and maintenance of health service buildings; medical pamphlets, equipment and supplies; public health, nursing and primary care; administrative occupational diseases; social policy; and social services for children, circulars and other families, people with disabilities and elderly people. Other topics: medical official toxicology and environmental health including chemicals in food and other Publications. consumer products, and the environment; pesticides; industrial chemicals; health consequences of smoking, radiation and noise; air and water pollution; and radiation biology. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 13 Literature Searching Database Subject coverage Types of Years Name sources covered covered King’s Fund The database reflects the King's Fund's focus on improving health and Journal articles from 1979 - database health care, covering policy and management of health and social care English-language services in the UK rather than clinical issues and treatments. Core subjects journals, books, include NHS management, social care, health inequalities, urban health and reports, pamphlets, regeneration, race and health, partnership working, primary care, mental web publications, health, public involvement, and workforce development in the NHS. strategic planning documents and government circulars. Official UK health policy documents and 'grey' literature from health and social care organisations. SOCIAL SCI Social Sci Search is a multidisciplinary index to the international literature of Journal articles, book 1972- SEARCH the social sciences providing complete bibliographic data, author abstracts reviews, discussions, and dated references. It corresponds to the social sciences citation index. editorial, meetings. Subjects covered include Anthropology, Archaeology, Economics, Hygiene and Public Health and many other areas. The databases noted in Table 4.1 are referred to as indexing or abstracting databases. This is because they provide the basic index information about an article such as author(s), article title etc, or in the case of an abstracting database the abstract or summary of each article is provided where available. Other useful resources to be found at include: • BioMed Central 140+ open access, peer-reviewed ejournals covering the whole of biology and medicine. • E-books On-line access to the full text of over 400 eBooks including titles from World Health Organisation and major publishers. The national collection focuses on mental health. • Proquest Search over 1500 full text journals online. • Pubmed PubMed is a service of the U.S. National Library of Medicine that includes over 16 million citations from MEDLINE and other life science journals for biomedical articles back to the 1950s. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 14 Literature Searching 4.2 On-line Searching On-line searching of databases is an interactive process. The searcher types in a keyword on the keyboard, and the computer displays the result as the number of references retrieved. The references themselves can be seen when the user issues a ‘display’ or ‘print’ command. Usually the commands are available via an on-screen link. The OVID online interface links it search across a number of the bibliographic databases noted in Table 4.1. An example of a basic search is shown below Subject: The management of asthma in general practice The following keywords were entered in turn and then combined: • asthma • general practice The following is displayed on the screen: Ovid MEDLINE (R) 2003 to February Week 1 2007 Search History Results Display 1 16867 DISPLAY 2 general 3630 DISPLAY 3 1 and 2 118 DISPLAY For each keyword entered the computer generates a result that indicates the number of articles found. The final line requests that the first two keywords are combined in one search. That is, find only those articles that appear under both subject headings. If the result is still very large it may be necessary to select subheadings to the keywords or add additional keywords to refine and narrow-down the search. Each search set can be displayed which shows the reference to each article found together with the abstract. References and abstracts can be selected and printed out, or transferred electronically to other computer software such as databases and word processing packages. Searching these databases can be a daunting task for the beginner. There are a large number of techniques available to optimise the search e.g. combining as shown above, but these are not always obvious to the novice searcher. If you are unfamiliar with these it is recommended that you work with a librarian who is trained in on-line searching. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 15 Literature Searching 4.3 Summary This section has introduced the main tools for finding research literature. These are the bibliographic databases that are designed to facilitate effective and efficient searching through the vast amounts of literature in order to find the articles that are of interest to you. However, before sitting down in front of a computer it is advisable to have a plan of the literature search you wish to conduct. Guidelines to help construct and implement a search plan are presented in the next section. 5. Planning and Conducting a Literature Search The objective of a literature search is to retrieve as much accurate information on a given subject as is possible from suitable sources. It is clear from this and the preceding sections that the novice reviewer is faced with a difficult task. The pool of available research literature is huge and only a tiny fraction of it, the particular subject of interest, needs to be located. Help is at hand of course in the form of bibliographic databases, but which ones should you use? This section presents some basic guidelines to follow when tackling a literature search. Like all types of investigation, an effective search requires careful planning. A badly organised search is likely to yield little relevant information and waste time. 5.1 General Points A search takes time to complete, even for the experienced reviewer. A reasonable continuous period of time should be set aside for task; an hour here or there is not sufficient. It is important to be systematic and record each step of your search. While there are no hard and fast rules for the period of the search it would be unwise to restrict it to recent years e.g. publications from the last 2 years. Finally, decide on your subject of interest and stick to it during the search. When searching on-line databases many interesting looking titles will appear - don’t get side tracked. 5.2 Bibliographic Databases The choice of bibliographic databases may well depend on the subject of interest and potential coverage by the different databases on offer. The main databases cover much of the mainstream medical and health literature, but at the same time do not cover all of the journals in all disciplines. 5.3 Keywords To increase the chances of retrieving relevant information from a search you need to create a description of the subject of interest. This takes the form of a set of words or The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 16 Literature Searching phrases, which are known as ‘search terms’ or ‘keywords’. Each search term or keyword identifies a part of the subject and provides a focus for the search. The process of creating keywords involves three stages: 1. Identify the key concepts in your research area 2. Analyse the concepts; extend their scope to find broader terms; define them with increasing precision to produce narrower terms; produce a list of synonyms; produce a list of related terms. 3. Map the list of key words or terms to the subject headings of each index to be used in the search. 5.4 Creating Key Terms: an example The area of interest is health visiting and the prevention of accidents to children in the home. The key concepts are health visitor, accident prevention, children, and home. To analyse the concepts it can help to create ‘spider diagrams’ as shown below (Figure 5.1). The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 17 Literature Searching Broader terms Broader term Community nursing Accidents Community health services Public health nursing ACCIDENT PREVENTION HEALTH VISITOR Related terms Health education Related terms Preventive health services Family support Wounds and injuries Social support Home care services Broader term Environment Broader term Public health Child welfare ACCIDENTS, CHILD HOME Narrower terms Narrower term Pre-school House calls Infants Figure 5.1. Key concepts and related terms Start the diagram by writing down the key concepts on a blank piece of paper. Carry out a brainstorming activity and make a note of related, broader and narrower terms as well as synonyms for each one. 5.5 Recording the Results The results of a search are references to articles. It is advisable to keep a copy of the articles it has retrieved. Computerised searches will generate reference lists that can be transferred electronically on to a computer and loaded into a database or word processor. Alternatively they can be printed out on to paper or e-mailed. The NIHR RDS for the East Midlands / Yorkshire & the Humber 2009 18 Literature Searching

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