Qualitative research is used to explore and understand people's beliefs, experiences, attitudes, behaviour and interactions. It generates descriptive, non-numerical data.  Qualitative research methods include:

• Documents - the study of documentary accounts of events, such as minutes of meetings
• Passive observation - the systematic watching and recording of behaviour  
• Participant observation – here, the researcher also occupies a role or part in the setting, in addition to observing
• In-depth interview - a face-to-face conversation to explore issues or topics in detail
• Focus group - method of group interview which explicitly includes and uses the group interaction to generate data.

Finding qualitative research

Use keywords and subect headings to identify specific types of research.

Keywords: 

phenomenological, "lived experience", "grounded theory", "life experiences", "focus groups" or interview.

Subject Headings: 

"Qualitative Research" or "Nursing Methodology Research" in Medline 

"Qualitative Studies" in CINAHL

Related Subject Headings such as Focus Groups, Interviews, or Descriptive Research can also be useful. 

Mixed Methods research integrates both Qualitative and Quantitative Research. It provides a holistic approach combining and analysing the statistical data with deeper contextualised insights. Using Mixed Methods also enables Triangulation, or verification, of the data from two or more sources.

Finding Mixed Methods research

Use keywords and subject headings to identify specific research.

Keywords:

“mixed model*” OR “mixed design*” OR “multiple method*” OR multimethod* OR triangulat* in CINAHL

mixed model* OR mixed design* OR multiple method* OR multimethod* OR triangulat* in Medline

Subject Headings:

"Multimethod Studies" or "Triangulation" in CINAHL

Study designs are the set of methods and procedures used to collect and analyze data in a study. The figure below shows the tree of possible designs, branching into subgroups of study designs by whether the studies are descriptive or analytic and by whether the analytic studies are experimental or observational. The list is not completely exhaustive but covers most basics designs.

Sourced from: Rodríguez-Ramírez, S., & Kim, S. J. (2022). How to ask the right question and find the right answer: Clinical research for transplant nephrologists. Frontiers in Immunology, 13, 879200. https://doi.org/10.3389/fimmu.2022.879200

Quantitative research is used to generate numerical data or data that can be converted into numbers. Study types that are used in the health and medical field include:  

• Case report or case series - a report on one or more individual patients.  There is no "control group" so this study type is considered to have low statistical validity
• Case control study - this studies patients with a particular outcome (cases) and control patients without the outcome. Is useful in aetiology (causation) research but prone to causation error
• Cohort study – identifies and follows two groups (cohorts) of patients, one having received the intervention being studied, and and one having not. Useful in both aetiology and prognosis research. Because the groups are not randomised, they may differ in ways other than in the variable under study
• Randomised Controlled Trial (RCT) - a clinical trial in which participants are randomly allocated to a test treatment and a control. This is considered the “gold standard” in testing the efficacy of an intervention. RCTs include methodologies - randomisation and blinding - that reduce the potential for bias and provide good evidence for cause and effect.

Finding quantitative research

Use keywords and subject headings to identify specific types of research.

Keywords: 

quantitative, survey, validity, variance, correlation or statistical

Subject Headings: 

"Validation Studies as Topic", "Statistical Distributions", "Mathematical Concepts", "Evaluation Studies as Topic" "Investigative Techniques" or "Meta-Analysis as Topic"

There are two broad types of evidence: secondary and primary. Note that we list secondary first because in Evidence Based Medicine it is the higher level of evidence and will probably be what you seek first in answering a clinical or research question.

• Secondary Evidence (filtered) -  is assimilated, or put together, from a number of quality primary studies on a topic. It includes systematic reviews, meta-analyses, and evidence summaries. This is sometimes referred to as filtered or pre-appraised evidence. You can find it in specialised EBP sources such as UpToDate, The Cochrane Library (notably in the Cochrane Database of Systematic Reviews) and JBI COnNECT+, and in health and medical databases such as MEDLINE, PubMed and CINAHL Plus with Full Text.

• Primary Evidence (unfiltered) -  consists of original individual studies such as controlled trials, cohort studies, and case studies. This is sometimes referred to as unfiltered evidence. You can find primary studies in specialised EBP resources such as The Cochrane Library, notably in the Central Register of Controlled Trials, and in health and medical databases. You can search for primary research in journal databases such as CINAHL Plus with Full Text and Medline.

For more information on Databases, see the Library Databases section of this guide.

The evidence hierarchy demonstrates the different levels of research literature. As you move up the pyramid, the study design is more rigorous and allows for less bias or systematic error. The amount of available literature decreases as you move up the pyramid, but increases in its relevance to the clinical setting.

"Research design and evidence" by CFCF [CC BY-SA 4.0] via Wikimedia Commons