Study Designs
It helps to have a good understanding of the basic designs of research studies in order to find the best possible evidence for your topic. See below for study design definitions and examples.
Definitions
Animal Research
A laboratory experiment using animals to study the development and progression of diseases. Animal studies also test how safe and effective new treatments are before they are tested in people.
Clinical Practice Guideline
A systematically developed statement designed to assist health care professionals and patients make decisions about appropriate health care for specific clinical circumstances.
Case-Control Study
The observational epidemiologic study of persons with the disease (or other outcome variable) of interest and a suitable control (comparison, reference) group of persons without the disease. The relationship of an attribute to the disease is examined by comparing the diseased and non-diseased with regard to how frequently the attribute is present or, if quantitative, the levels of the attribute, in each of the groups.
Case-Series
A group or series of case reports involving patients who were given similar treatment. Reports of case series usually contain detailed information about the individual patients. This includes demographic information (for example, age, gender, ethnic origin) and information on diagnosis, treatment, response to treatment, and follow-up after treatment.
Cohort Study
The analytic method of epidemiologic study in which subsets of a defined population can be identified who are, have been, or in the future may be exposed or not exposed, or exposed in different degrees, to a factor or factors hypothesized to influence the probability of occurrence of a given disease or other outcome. The main feature of cohort study is observation of large numbers over a long period (commonly years) with comparison of incidence rates in groups that differ in exposure levels.
In Vitro Research
In the laboratory (outside the body). The opposite of in vivo (in the body). (NCI Dictionary of Cancer Terms)
Meta-Analysis
A quantitative statistical analysis of the data from multiple studies, it can be done as part of a systematic review or separately.
Observational Study
A family of studies in which investigators compare people who take an intervention with those who do not. The investigators neither allocate patients to receive the intervention not administer the intervention. Instead, they compare records of patients who had taken an intervention and been treated in routine practice with similar patients who had not taken the intervention. The most common observational designs are case-studies, case-series, case-control studies, cohort studies, and historically controlled studies.
Randomized Controlled Trial
A study in which subjects are randomly assigned to groups, usually intervention and control groups, to receive or not receive an experimental preventive or therapeutic procedure, maneuver, or intervention. The results are assessed by rigorous comparison of rates of disease, death, recovery, or other appropriate outcome in the study and control groups.
Systematic Review
The application of strategies that limit bias in the assembly, critical appraisal, and synthesis of all relevant studies on a specific topic. Systematic reviews focus on peer-reviewed publications about a specific health problem and use rigorous, standardized methods for selecting and assessing articles. A systematic review may or may not include a meta-analysis, which is a quantitative summary of the results.
Citations for Definitions:
Center for Evidence Based Medicine (2022) Glossary
National Cancer Institute (NCI). NCI Dictionary of Cancer Term.