Healthcare Research and Evidence Based Practice: Types of Research

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.

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.

Please note that a research study does not have to be exclusively quantitative or qualitative. Many studies will use a combination of both types of research.

In the Dictionary of Statistics and Methodology, Mixed-Method Research is defined as:

"Inquiry that combines two or more methods. This particular term usually refers to mixing that crosses the quantitative-qualitative boundary. However, that boundary is not necessarily the most difficult one to cross. For example, mixing surveys and experiments (both quantitative methods) may require more effort for many researchers than combining surveys and focus groups (the first quantitative and the second qualitative)."

Mixed method research. (1999). In Vogt, P. W. (Ed.). Dictionary of statistics & methodology (2nd ed.).