A research project, a detailed examination or a procedure.
case study A method designed to give a detailed description of a single case (
case report) or of more than one case (
case series). It may be used to describe a rare condition, a new procedure and how cases with the same condition vary.
case-control study A longitudinal retrospective study in which two groups of individuals, the
cases, people who have the disease, and the
controls who do not have the disease are compared for specific characteristics that may be more commonly found in the diseased group (risk factors) than in the control group. This type of study may be affected by confounding factors (e.g. imprecise records, mismatch of the two groups).
cohort study A longitudinal study in which a group of subjects, called a
cohort, is followed over a period of time. It can be either followed into the future (prospective study) or analysing past records (retrospective study). It is usually compared to another cohort, the controls, who do not possess the attribute being investigated.
cross -
over study An experimental design in which the effect of two or more treatments on a particular feature (e.g. a drug therapy) are given to each individual, one treatment after the other in random order.
cross -
sectional study A design in which the prevalence of a condition in a group of individuals is determined at a given point in time.
See longitudinal study.
double -
blind study An experimental design in which neither the person receiving the treatment (or recording the results of a test) nor the person administering it, knows the identity of the treatment or test.
See randomized controlled trial.
longitudinal study A design in which subjects are followed over a period of time with data collected at various intervals.
Examples: prospective study, retrospective study.
See cross study.
- sectional.
observational study A research method designed to draw inferences about the possible effect of exposure on an established outcome (e.g. a disease, a therapy) without the investigator's intervention.
Examples: case-control study, cohort study, cross-sectional study.
prospective study A longitudinal study aimed at establishing an association between a specific risk factor (or therapy) and the development of a disease (or cure). Two groups of individuals (cohorts), one group exposed to a specific risk factor and the other not exposed, are examined over a period of time and the incidence rates of the outcome are compared between the two groups. It is a more powerful design than a retrospective study to determine an association.
See randomized controlled trial.
retrospective study A longitudinal study aimed at establishing the presence of specific factors that are associated with a given outcome (e.g. a disease, a cure) by analysing the past records of patients with the outcome as compared to patients without the outcome.
Example: case-control study.
single-blind study A method of testing in which the treatment assignment or procedure is unknown to the patient or subject.
See placebo.
triple -
blind study An experimental design in which the subject, practitioner and the person administering the test do not know the identity of the treatment or test.
See randomized controlled trial.