However, you should of course also find some eligible references. Maybe some of the search terms will generate a lot of false hits.
If so, you might consider to remove them. You can use the NOT operator again in order to analyse the search. Analyse the result. If you do not find any relevant hits, consider excluding the term from the search strategy. In addition to the search tips below, the database sheet made by the search group at KIB is useful for creating and translating search strategies.
You are probably quite familiar with PubMed, and it is an easy database to start with. There are, however, a few things to consider:. Ovid is a database platform used for many different databases.
In Ovid it is possible to use proximity operators, truncate without any limitations and search for all phrases as opposed to PubMed, which is limited by the phrase index. It is also easier to structure comprehensive and advanced search strategies. As in the example below, we deconstruct our search strategy into lines and then combine them, first each line within a search block with OR, then the search blocks with AND.
There are several different options for searching in Embase via embase. In the example below, the search strategy is divided in lines as in Ovid: one for each Emtree term, one line for all free-text. These are then combined into one search block. You can access the Emtree terms in the top menu under "Browse". Web of Science Core Collection is a multi-disciplinary database that includes research areas other than biomedicine and health.
There is no controlled vocabulary in Web of Science and only free-text searches are possible. To be systematic implies a focus on structure, organization and documentation. As in all research, the review process should be transparently documented in all parts, reported clearly in the final publication, and reproducible.
As a support in the review process there are the PRISMA Guidelines : "an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. According to PRISMA, the search strategy should be reported in full for at least one database; however, we recommend attaching all search strategies as an appendix to the published article.
The majority of journals allow you to upload supplemental material. If the complete search strategies are attached, you only need to briefly describe the search process in the methods section and thereafter refer to the supplemental material section. As with a clinical trial, a protocol should be established for a systematic review; preferably, it should also be registered. There are several reasons for this. For instance, it increases the overall transparency of the review, making it more scientifically sound.
Additionally, the registration of the protocol also adds visibility to your review. This can help to avoid duplication of the work. It's also possible to publish protocols in the journal Systematic Reviews. Systematic literature searches always produce a large amount of references. Also, when searching in several different databases many duplicate references will appear — i. Reference management software , such as EndNote, is recommended for collecting, storing and organizing your references.
Using a reference manager, you can organize your references in different groups, for example, included and excluded studies. You can also remove duplicates by sorting the references by title or by using the duplicate functionality. Wichor Bramer, information specialist at Erasmus MC , has developed an method for removing dublicates from different databases in Endnote. The method exists in an unpublished and relative simple version presented here. However, Wichor Bramer and co-authors have also later published a modified and more advanced version Bramer et al.
Go to Duplicates and Preferences in Endnote. Select fields for each comparison below and click on Find Duplicates under References and remove all duplicates. Repeat the procedure for each comparison. Follow the procedure in step 2, but de-select all duplicates and select the real duplicates instead.
However, EndNote and other types of reference managers have limitations when it comes to supporting the systematic review process. Other software has therefore been developed and is dedicated to supporting the systematic review process, for instance in the screening of abstracts and references according to inclusion and exclusion criteria. For the time being, KI offers no institutional licens on this kind of software. An thorough summary of available tools can be found at Systematic Review Toolbox.
As the literature search is a fundamental part of a systematic review, it's important that the search strategy is of high quality. To ensure this, and to avoid errors, there are several options. In either case, it's good if a second person has a thorough look at the search strategy. PRESS was originally published in —, but was revised in The PRESS checklist was originally made for expert searchers, such as librarians, but can also be used by students and researchers when creating more extensive search strategies.
If you are a bachelor's or master's student, or a doctoral student writing a literature review for the half-time summary, please book a consultation for a certain time. If you're a researcher or a doctoral student preparing a systematic review, please contact the search group. Systematic reviews.
This page is aimed primarily at researchers and doctoral students. If you are a Bachelor's or Master's student, you will find our guide Structured literature reviews — A guide for students useful. As a student you should rather do a structured literature review, including only certain aspects of the methodology described on this page.
As a doctoral student at KI, you are allowed to include a systematic review as part of your thesis. The Committee of Doctoral Education also emphasises the importance of a structured review of the literature in the thesis "kappa".
A literature review of your research field is now mandatory in the half-time summary. What is the difference between a systematic review and a traditional review? There are four essential criteria for a systematic review: It should be exhaustive : all relevant literature in a research field should be included. A rigorous methodology must be followed throughout — from defining the research question, writing a protocol and searching the literature, to gathering, screening and analysing.
The entire process should also be thoroughly documented. At least two people should be involved, particularly for screening articles and extracting data.
Plenty of time resources are needed, but also in terms of availing yourself of others' expertise — for instance in database searching — and tools and software. Traditional scoping review Systematic review Aim To gain a broad understanding, and description of the field Tightly specified aim and objectives with a specific review question Scope Big picture Narrow focus Planning the review No defined path, allows for creativity and exploration Transparent process and documented audit trail Identifying studies Searching is probing, moving from one study to another, following up leads Rigorous and comprehensive search for ALL studies Selection of studies Purposive selection made by the reviewer Predetermined criteria for including and excluding studies Quality assessment Based on the reviewer's opinion Checklists to assess the methodological quality of studies Analysis and synthesis Discursive In tabular format and short summary answers Methodological report Not necessarily given Must be presented for transparency.
Systematic search techniques. Sensitivity, specificity and precision To construct an exhaustive search strategy, and at the same time avoid too many references to screen, is a challenging task. Modified figure from the SBU handbook, p. Do not reinvent the wheel Before you create a search strategy, it is a good idea to look at what has already been done. Create search blocks A well-defined and clear research question is an essential starting point for a systematic search.
We will use this research question as an example: Does routine use of inhaled oxygen in acute myocardial infarction improve patient-centered outcomes, in particular pain and death? Find search terms In every search block, you should include all relevant search terms and variants, combined with the boolean operator OR.
Subject headings In many databases, articles are for better retrieval indexed with subject headings or controlled terms from a thesaurus. Free-text terms Include all the relevant synonyms and spelling variations in title and abstract from the key articles and other relevant studies retrieved by the test search.
Introduction Toggle Dropdown Different types of literature review Developing the research question Developing your search strategies Toggle Dropdown Search strategies Recording your systematic searching Systematic reading of the literature Writing your literature review Software tools Citing your sources References.
Citing your sources Citing your sources Citing and referencing your sources is an essential part of your literature review. Referencing is the process of clearly and consistently acknowledging all the information sources you have used by: providing citations in your essay where you have quoted or paraphrased another's words or ideas providing a reference list or bibliography at the end of your assignment.
Use of referencing software to manage your citations The Library provides free access to the EndNote software tool which can be used to manage your citations in a number of ways. You can use EndNote to: Collect and create a list of references from your research you can import these from online sources such as the Library catalogue, Library databases and Google Scholar or enter them manually yourself Add categories and notes to these references and attach copies of the actual articles if you wish Insert in-text citations in an assignment or paper, and build a Bibliography or List of References automatically formatted in the style you have chosen eg, APA6, Harvard AGPS.
EndNote can assist and guide you, but it: Cannot teach you how to reference correctly. It is important to understand referencing principles before you use any citation manager. Cannot check or correct references in your library which includes flawed data.
When working on a systematic review, you are likely to use a PRISMA flow diagram to ensure you properly report your methods. Using a reference management package can help you to meet PRISMA requirements, by making it easier to track the number of references identified, duplicates identified, references screened, records included or excluded , full text articles reviewed. Search this Guide Search. Reference management software This guide introduces reference management software and the options available to users of UCL Library Services.
What is reference management software Why use reference management software? Using reference management software for assignments Using reference management software for independent research Using reference management software for systematic reviews How to use reference management software at UCL Toggle Dropdown Which software should I use?
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