Filtering the Literature for Research Studies: "Magnet in a Haystack"
Doing a literature search to support evidence-based practice requires the use of search strategies to filter results from article databases. Like a magnet in a haystack, a search strategy will help you to systematically apply limits to database search results to sift through the profusion of published literature.
Limits to use:
- Database limits may include choices for filtering publication types: case studies, editorials, news articles, as well as higher levels of evidence such as clinical trials, systematic reviews, and meta-analyses. Limiting by publication type is one way to ensure that the research retrieved was based on a more rigorous methodology and thus reflects a higher level of evidence.
- Date of publication limits are usually available and can help reduce your set of results. Date limits are particularly helpful when you have too many results, or you have a clinical topic and wish to retrieve only the most recent literature.
- Age group: databases with limits for age group provide a useful way to limit results when an age group limit is relevant for your topic. When you wish to limit results by age group, use the limit feature rather than putting in your own keywords. Using these limits ensures a standard approach to narrowing your search, rather than using your own keywords such as "elderly" or "pediatric."
- "Peer-reviewed articles," "research," "evidence-based," language, species, and other subsets for topics may be available. Use with care, and be sure to read the description of what they mean, as they may inadvertently apply limits you don't want!
Limits to avoid:
- "Full text" or "full text available," limits may appear and you should avoid using these! At NYU we subscribe to full text in many ways and from multiple vendors and packages. From individual citations you will see the NYU full text links. Avoid biasing your search results by using the database full text limit, as that will limit to just articles available from that individual service.
The instructions below depict beginning strategies for limiting by publication type (or methodology) in each selected database.
Limiting (filtering) strategies:
- Limiting in CINAHLPlus (limit to "Research," "peer-reviewed," etc.)
- Limiting using Popular Filters in Medline via PubMed
The InterTASC Information Specialists' Sub-Group Search Filter Resource is a collaborative venture to identify, assess and test search filters designed to retrieve research by study design.
Health services filters that you can use when you are searching Medline for articles relevant to specific aspects of health services resear
CINAHLPlus Indexes >3,800 journals from the fields of nursing & allied health, with indexing for selected journals back to 1937. Topics covered are related to nursing, PT, health education, social service, healthcare, OT, & related disciplines.)
CINAHLPlus at NYU is available from: http://arch.library.nyu.edu/databases/proxy/NYU00202
More limiting strategies in CINAHLPlus:
- Limit to publication type: Systematic Review (indicates a research process in which a concept is identified and the research which has studied it is analyzed and evaluated. Results are synthesized to present the current state of knowledge regarding the concept. Includes integrated or integrative reviews).
- Browse the many Publication types; notice the range from case study or letter (lower levels of evidence) to Systematic Reviews and Clinical Trials (higher levels of evidence).
- Using the CINAHL “Evidence-based Practice” limiter includes “Research” articles (including systematic reviews, clinical trials, meta analyses, etc.) as well as articles from evidence-based practice journals, articles about evidence-based practice, and commentaries on research studies (applying practice to research). Use with caution; every result may not be an evidence-based study. More about the evidence-based practice limiter.
- Advanced Searchers:
- Limit using Clinical Queries filter in five research areas: Therapy, Prognosis, Review, Qualitative, Causation (Etiology)
- High Sensitivity is the broadest search, to include ALL relevant material. It may also include less relevant materials.
- High Specificity is the most targeted search to include only the most relevant result set, may miss some relevant materials.
- Best Balance retrieves the best balance between Sensitivity and Specificity.
–A detailed explanation of the strategies behind these limits can be found at http://hiru.mcmaster.ca/hiru/HIRU_Hedges_home.aspx
Medline (via Pubmed or Ovid) is the premier source for bibliographic coverage of biomedical literature. Contains >20 million records from more than 5200 journals. (More about Medline)
Unlike CINAHLPlus, Medline does not have a publication type that simply says “Research,” and it does not have a filter for "peer-reviewed," but you may filter your results for higher levels of evidence by limiting to Article type, for example,
“clinical trial or meta-analysis or randomized controlled trial.”
Medline (via PubMed) @ NYU is available from: http://arch.library.nyu.edu/databases/proxy/NYU00068
Additional research methodology filters are available in PubMed.
Clinical Queries or Topic-Specific Queries apply preformulated search strategies to topics for clinicians and health services researchers.
If the popular Filters described above do not include your "study type," try a search using PubMed MeSH terms available for study methodologies:
More about PubMed Filters:
- Health Services Research (HSR) filters: A search interface to find PubMed citations relating to health care quality or to health care costs (Pubmed equivalents)
- Healthy People 2020: Structured Evidence Queries (SEQs) - to retrieve citations to published literature related to Healthy People 2020 topic areas and objectives.
- NLM resources for CER Queries (Comparative Effectiveness Research)
Unlike CINAHLPlus, Medline does not have a publication type that simply says “Research,” but you may filter your results for higher levels of evidence by limiting to Article type, for example,
“clinical trial or meta-analysis or randomized controlled trial.”
Medline (via Ovid) at NYU is available from: http://arch.library.nyu.edu/databases/proxy/NYU00117
More Medline (via Ovid) Limits:
Using the EBM Reviews limit will allow you to ‘OR’ together any of the following limits: Cochrane Topic Reviews, ACP Article Reviews or DARE Article Reviews.
Limiting using “Clinical Queries” will restrict retrieval to clinically sound studies in nine categories provided, and the emphasis may be Sensitive (i.e., most relevant articles but probably some less relevant ones), Specific (i.e., mostly relevant articles but probably omitting a few), or Optimized (i.e., the combination of terms that optimizes the trade-off between sensitivity and specificity). A detailed explanation of the strategies behind these limits can be found at http://hiru.mcmaster.ca/hiru/HIRU_Hedges_home.aspx
PsycINFO (via Ovid) (1887-present.) Abstracts and citations to the scholarly literature in the psychological, social, behavioral, and health sciences, with material of relevance to psychologists and professionals in related fields such as psychiatry, management, business, education, social science, neuroscience, law, medicine, and social work plus many health-related fields, including all aspects of mental health, nursing, health administration, pharmacology, rehabilitation, and epidemiology.)
When you have performed a search by topic in PsycINFO, you may then choose to restrict your search to one or more “Methodology.”
You may choose to scroll through your retrieved citations and notice the “Methodology” field to see what kind of article you are viewing. Or you may LIMIT your search electronically.
PsycINFO (via Ovid) is at NYU is available from: http://arch.library.nyu.edu/databases/proxy/NYU00201
PsycINFO (via APAPsycNet) (1887-present.) Available from: https://arch.library.
Proquest is a multidisciplinary resource for research on contemporary topics or for the beginning stages of a research project.
Proquest at NYU is available from: http://arch.library.nyu.edu/databases/proxy/NYU02080
Check the Limit boxes as shown to search only scholarly journals or peer-reviewed journals. Leave the box empty to include other sources in your search.
A publication is considered to be Scholarly if it is published for an academic audience by a recognized society with academic goals and missions.
A publication is considered to be Peer-reviewed if it has been assessed by other scholars in the same field for quality of scholarship, relevance to the field, and appropriateness for the journal. Most (but not all) scholarly publications are peer reviewed. Some trade publications and magazine are also peer reviewed.
Limiting to "Peer Reviewed" Articles
"Peer reviewed" (or "refereed" journals) are those that subject content to a critical review by other experts in the field prior to accepting a manuscript for publication. Thus, limiting your literature search to the peer-reviewed journals ensures a higher level of scholarship and research methodology. Magazines, trade journals, and newspapers tend to be "non-peer-reviewed," meaning perhaps just the editor or someone who is not an expert in the field has reviewed the content before publishing. How do you know if a journal citation is from a peer-reviewed journal?
- You can do a journal title search in Ulrich's Global Serials Directory. The symbol: indicates a journal is "refereed"
- You can look for the "Limits" feature in many databases to narrow search results by publication type.