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Finding Qualitative & Quantitative Research Articles

For Students in BS Respiratory Care Program

Advanced Search Strategies

Advanced Search Strategies

Boolean operators

As a student in allied health and nursing disciplines, you will be required to do advanced research in many of your classes. In order to build a successful search strategy, you need to understand the concept of Boolean searching. The following video offers a quick overview. 

 Boolean operators infographic, with Venn diagrams illustrating the operators OR, AND, and NOT


Truncation/wildcard is a search technique which allows you to search databases for variant spellings of words simultaneously. It is very useful to take into account plural and singular forms of a noun. Truncation is placing a symbol after the root of a word.

The asterisk * [Shift and 8 on a standard US/UK keyboard] is used by many databases--Scopus, Web of Science, Medline, and CINAHL--as a truncation command.


  • collaborat*

Will retrieve collaborate, collaboration, collaborative, collaborations, collaborating

  • child*

Will retrieve child, children, childhood, childbirth, children's


However, this doesn't work with all words. Truncation at col*

Will retrieve too many and too many unrelated results such as colonel, collection, college, cold, Colombia



Wildcards are rather like truncation, but instead of allowing for variation at the end of a word, it allows for variation in a character in the middle of a word. Wild cards are especially useful for taking into account variations in spelling. For example, many words can be spelt with an s or a z, e.g. realise/realize. You could use the OR operator to get around this, but wild cards are much neater:


In the example above, any character can appear between the i and e. Again, syntax can vary between databases, sometimes ? is used - check the help pages!

Phrase Searching

In databases, you can use quotation marks to isolate a phrase. For instance, if you're looking for resources on natural selection, you'll want to conduct the search with phrase searching. If you search ["natural selection"], your results will include only resources that include the entire phrase. If you instead search for just [natural selection], your results will include the resources with that phrase, but it will also include all resources that have the word "natural" and the word "selection."

For Any Database

These strategies can help you locate qualitative and quantitative articles as you search library databases. For biomedical research, we recommend you begin from the ADVANCED SEARCH page in research databases. 

Prerequisite: Always Do This

Limit your searches to Peer Reviewed articles. (This strategy will provide you with the most results.) Research studies that use qualitative and quantitative methods are published in peer reviewed journals. Not every article in a peer reviewed journal will be a research study, but limiting your results to articles in these journals will help you narrow the pool of articles you are looking through.

Strategy 1: Use Subject Headings 

Databases use controlled keywords (known as thesaurus or subject terms) to categorize each record stored. PubMed and MEDLINE, for example, both use Medical Subject Headings (MeSH), a highly structured index of terminology. The subject headings vary for each database according to their indexing system.  The term "qualitative research" is indexed in PubMed as "Qualitative Research" or "Nursing Methodology Research", while in CINAHL the subject heading "Qualitative Studies" is complemented by more detailed terms, including "Phenomenological Research" and "Grounded Theory." See next tabs for more detailed information on finding articles in specific databases. 

The video below explains how to use MeSH in CINAHL, but the basic principle applies to searching by subject heading in MEDLINE and PubMed.

Strategy 2: Use Limiters

Limit to Research Articles and/or Peer-Reviewed Journals. Limit your results to publication types that are quantitative or quantitative by definition. For quantitative, look for things like Meta-analysis, Clinical Trial, Statistics, Tables/Charts, etc. For qualitative, look for publication types such as  Anecdote, Interview, Metasynthesis, etc. 

Strategy 3: Use Keywords

This strategy uses text that might specifically identify the type of research you're seeking. These keywords will be used to search the titles, abstracts and keywords of records held in the databases.

For Qualitative Research, some keywords include: qualitative, ethnograph*, phenomenol*, ethnonurs*, grounded theor*, purposive sample, hermeneutic*, heuristic*, semiotics, lived experience*, narrative*, life experiences, cluster sample, action research, observational method, content analysis, thematic analysis, constant comparative method, field stud*, theoretical sample, discourse analysis, focus group*, ethnological research, ethnomethodolog*, interview*.

For Quantitative Research, use keywords that might specifically identify quantitative research and that search the titles, abstracts, and keywords of records held in the databases. Some keywords include: Correlational design*, Effect size, Empirical research, Experiment*, Hypothesis, Quasi-experiment*, Reliability, Sampl*, Validity, Variables, Chi Square Test, Analysis of Varience, Confidence intervals, Statistic*.

Strategy 4: Search Using Prefab Search Filters, or Hedges

Search filters are pre-tested strategies that identify the higher quality evidence from the vast amounts of literature indexed in the major medical databases. Filters exist for most types of experimental design, and are comprised of index terms relating to study type and specific terms associated with the methodological description of good experimental design. You can use the filter and then combine the results with your subject. 


Combining Search Strategies

It is important when searching databases which have a thesaurus and which tag articles with subject headings (Medline, CINAHL, etc.) that your search strategy combines (with OR) both relevant subject headings and keyword/free-text searches on a particular concept.

Context for Understanding: Pyramid of Evidence

pyramid of evidence graphic which shows rigor in relationship to type of research


It helps to know about the different sorts of evidence used in healthcare research--knowing what is defined as a filtered vs. unfiltered research study will help provide context for understanding Quantitative and Qualitative research. 

Types of Scholarly Articles

Scholarly journals contain many types of articles. Here are some of the different formats you may see, and some of their defining characteristics:

Review articles (AKA filtered information: includes literature reviews, systematic reviews, meta-analyses):

  • Summarize research on a particular topic
  • Evaluate research on a particular topic 
  • Analyze research on a particular topic
  • Provide no original research on the topic
  • Are often peer reviewed
  • Are considered secondary sources

Primary research articles (unfiltered information: research studies, reports, clinical reports):

  • Ask a research question
  • Identify a research population or group
  • Describe a research method
  • Test or measure something
  • Summarize the results
  • Are almost always peer-reviewed
  • Are considered primary sources

Case studies (unfiltered information: includes case reports)

  • Provide a detailed analysis on one patient/case
  • Draws conclusions only on that one patient/case
  • Ask new questions, suggest new avenues of research
  • Are almost always peer reviewed
  • Are considered primary sources


  • Provide a professional opinion a a particular topic
  • Are selected for publication by an individual editor instead of a peer-review process
  • Are considered primary sources