Sep 19, 2019
Sensitivity & Specificity: demonstrating finding evidence using MeSH thesaurus terms
The concepts of sensitivity and specificity, as they apply to a database search strategy, refers to doing a wide search for evidence or a narrower one. A wide or sensitive search strategy will aim to retrieve a larger number of results relevant to your topic of interest. It will be more time consuming and will involve more work screening out irrelevant results. A sensitive search is more likely to be used for knowledge support eg producing a publishable systematic review or a substantial report. A more narrow or specific search is one that seeks to find some representative results for decision support where timely evidence is a priority eg creating a quick report for discussion on a topic or informing a patient’s need for a review of their medication. Thesaurus terms such as MeSH for Medline refers to the indexing system unique to each database you might use. PubMed is a host platform for Medline so that it uses MeSH terms. These terms are highly recommended for use when creating a search where they are found to be appropriate. The more closely their meaning matches concepts within your enquiry topic the more specificity you can introduce into your search.
Sep 19, 2019
Searching for evidence using successive fractions
Using successive fractions involves successively reducing search results to the lowest number by putting the main concepts of an enquiry in, one after the other, adding them together in sequence and looking at the results of each line in order to find the most relevant results. The successive fractions technique is also known as divide and conquer or file partitioning. It allows you to cherry-pick evidence from several small searches each with a slightly different focus on your enquiry but with high relevance according to that focus. It is also a useful strategy for scoping the range of evidence available in response to an enquiry. The Advanced Search Builder in PubMed is used to demonstrate the use of successive fractions. A good way to prepare for this kind of search is to use a framework. Using a framework helps to structure the question by clarifying the main concepts to focus on and the particular choice of the framework you use depends on the topic of interest. Your topic may not fit perfectly into any chosen framework and not all the available concepts within the chosen one have to be used. This video demonstrates the use of the PICOS framework.
Sep 19, 2019
Forward citation searching
Forward citation searching refers to the practice of looking for articles that cite (reference) a known article of interest in an attempt to find other and more recent evidence that is relevant to your topic. It is important that the article that you start with is relevant in terms of at least one of the elements of your enquiry.
Sep 19, 2019
Demonstrating finding grey literature and secondary sources
Grey literature refers to documents that are either unpublished or have been published in non-commercial form. The term includes: government reports, statistics, policy statements and guidance; conference proceedings and theses and dissertations. You may not have time to do a search on bibliographic databases for evidence but even if you do have this time you should always start your enquiries with a search of any of the relevant policy documents that are available to you in your local context. In the UK these might include searching the websites of NICE / The King’s Fund / UK.gov / NHS etc. for documents relevant to your enquiry. It can be important that you find and use the most recent update of any grey literature that you are interested in e.g. in the case of national health guidance.