Note: this section provides some tips on the more advanced aspects of searching such as: the difference between sensitivity versus specificity, what is MeSH (including use of MeSH tree, exploding, focusing, use of subheadings) and what are filters. For a comprehensive listing of Primary and Secondary sources via RMH, click here. Click here to see a pdf from Oxford CEBM on Asking Clinical Questions: formulatimng a search strategy. 1. The 12 key steps of (generic) electronic searching 1. State your research topic as a single question (e.g., “Does physical fitness improve sleep?”). 2. Identify the separate concepts that make up the question. 3. Use the electronic Thesaurus to find descriptors that represent the first concept. 4. If you do not find relevant descriptors, search free-text words and phrases instead. 5. Use OR to combine all descriptors or free-text terms that represent the concept. 6. Repeat steps 3 through 5 for each remaining concept in your search question. 7. Use AND to combine the ORed sets that represent the main concepts. 8. Review some of the retrieved records to assess their relevance. 9. If necessary, revise your search strategy and repeat the search. 10. Limit by language, publication year, form/content type, document type, etc., as desired. 11. Mark the most relevant records in your search. 12. Print or download your marked records.

2. Sensitivity versus specificity Increase specificity of your search by: Focusing or narrowing your question Limit your search by age of the patient (paediatric, elderly), type of article (randomised clinical trial, review, meta-analysis), language (English), type of publication  Use the MESH heading instead of free text or text word search Use particular MESH subheadings Combine searches such as hypertension and diuretics or asthma and corticosteroids   Increase the sensitivity of a search by: Making your question more broad (instead of looking at hypertension in just diabetic patients, look for hypertension irregardless of associated diseases) Don’t employ the strategies listed above Expand the time frame of your search (in Medline you can search all the way back to 1966)

3. MeSH introduction Many databases, such as Medline, use a thesaurus to enable more effective searching. A thesaurus is a controlled vocabulary which is used to index information from journals. Instead of allowing numerous variations in words and phrases it seeks to 'control' the vocabulary by grouping related concepts under a single preferred term. A thesaurus will typically contain keywords, definitions of those keywords and cross-references between keywords.  There are several reasons for using the thesaurus of a database. As a thesaurus is a controlled vocabulary, all indexers use the same standard terms to describe a subject area, regardless of the term the author has chosen to use. So, for example, all items relating to heart attacks are indexed as "myocardial infarction", whether or not the author has actually used the term "myocardial infarction". Each of the MeSH (Medical Subject Headings) terms or keywords represents a single concept appearing in the medical literature. As important new concepts appear, a new MeSH keyword is created. When a new reference is added to Medline, indexers choose and add the appropriate MeSH keywords (usually 10 to 20) to represent the contents of the article. If you look at a Medline reference, you will notice keywords towards the end. To complicate matters, different databases have different thesauri (i.e., an equivalent of MeSH). CINAHL, EMBASE and PsycInfo each have their own thesauri - consequently, you can not merely search MeSH within Medline and expect to apply the same MeSH terms for other databases! Where a database does not have a controlled vocabulary (thesaurus) you are free, of course, to search using any terms (MeSH or non-MeSH). Note too that when using a controlled vocabulary facility you usually also have the option to 'explode' the search and so avoid more distal citations (see below). In addition, you have the option to Focus your search - i.e., choosing citations that have the subject as the major component (see below). There are also subheadings (different to each MeSH term) to choose from, if needed. For more information on MeSH, see: http://www.nlm.nih.gov/mesh/MBrowser.html and http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=mesh     Tip:  To apply MeSH for Medline, CINAHL or PsycInfo via Ebsco, ensure the 'Suggest subject terms' box is ticked. Note, too, that if you have more than one database open, this facility is no longer available. The MeSH tree The keywords which make up MeSH are arranged into hierarchical structures called trees, starting with broad terms which branch off into increasingly narrower or more specific terms. Indexers are instructed to always use the most specific term. Thus, an article covering obesity in diabetics will be indexed using the term OBESITY IN DIABETES and not using the broader term DIABETES MELLITUS. An article indexed as DIABETES MELLITUS will usually discuss diabetes in general without going into very much detail on specific aspects. The tree structure is helpful when searching as it helps you to identify broader and narrower terms.     Tip: If you wish to see how your search term fits in with the MeSH tree, use the Permuted Index (inverted index structure), where available.   Exploding your search The tree structure of MeSH allows you to explode your search, which is less dangerous than it sounds! This means that you can search for a keyword plus all its narrower terms simultaneously. For example, if you wanted to run a comprehensive search for references relating to diabetes, you could explode the keyword DIABETES MELLITUS to pick up all narrower terms: Diabetes Mellitus Diabetes Mellitus, experimental Diabetes Mellitus, insulin-dependent Diabetes Mellitus, lipoatrophic Diabetes Mellitus, non-insulin-dependent Diabetic Angiopathies Diabetic Coma etc. The Explode feature is very useful for obtaining comprehensive coverage of a subject area (i.e. increasing the number of your results).    Tip: If results are too few, use the 'explode' command, limit your use of subheadings (or try none); also consider using a text words search too (see below). Focusing your search Indexers assign up to 20 MeSH keywords to an article. However, they are also able to assign particular weight to certain keywords by designating them as major headings. Major headings are used to represent the main concepts of an article. You are able to search for major headings. The keywords assigned by indexers are listed towards the end of each reference. Here is an example of a search result, showing keywords: TI: How easy are randomised controlled trials in epilepsy to find on Medline? The sensitivity and precision of two Medline© searches. AU: Marson-AG, Chadwick-DW MeSH: Abstracting-and-Indexing-standards; Epilepsy; Evaluation- Studies; Medline-standards; Periodicals-standards; Randomised-Controlled- Trials-statistics-and-numerical-data; Sensitivity-and-Specificity; Subject- Headings    Tip: If you need to look up synonyms of a term, use the Thesaurus facility in Cochrane.  What if you have no MeSH keyword? Although keyword searching using MeSH terms is a more precise way of searching, this won't always work for you. There may be times when there is no MeSH keyword for the subject you are searching; for example, until 1997, there was no MeSH keyword for "evidence based medicine". In the absence of MeSH keywords, you need to search free text. Free text searching is a method of searching by using words and phrases from the title, abstract and keywords of references. Free text searching is also useful for broadening your search. Also, some databases do not map against a controlled thesaurus (MeSH or otherwise) and so with these you have no choice but to apply keyword searching.      More Search Tips    You will generally find that long search strings can be non-productive. If one element is wrong, the whole search becomes invalid. By taking a step-by-step approach, you are able to see what a particular database has got and what it hasn't, and so refine your search strategy accordingly. if a database has an Advanced search facility, use it (provides more options) Choose subheadings only as needed (and if available). If results are too many, consider applying selective subheadings. 3. Filters Methodological and clinical filters are search strings that can be added to a search to focus the search. Typically, filters are used to find systematic reviews and/or results that emphasise therapy or diagnosis or aetiology/harm, etc.  You will be pleased to know that both PubMed Clinical Queries (click on 'Clinical Queries' on the PubMed menu) and Ovid have ready-made filters.  However, if you prefer to add them in yourself (unfortunately, you can't just copy and paste) then check these ones out: SIGN filters http://www.sign.ac.uk/methodology/filters.html Inter-TASC:  http://www.york.ac.uk/inst/crd/intertasc/   See also: MedFetch http://www.medfetch.com/testdrive.htm

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