Experimental Studies

In contrast to observational studies, experimental studies involve the experimenter allocating subjects to different exposures and then observing differences in disease (or other health) outcomes between exposure groups. Generally, they are time-consuming & expensive, therefore, in experimental studies we compare intervention groups and control groups.

Principles

 * 1) The individuals (or communities) will be assigned to the drug or intervention randomly → ensuring that the groups are very similar except for the intervention → removing much of uncertainty of observational studies.
 * 2) Follow up
 * 3) Incidence
 * 4) Temporality is clear, no confounding / bias
 * 5) They have a Gold standard to compare against

Examples

 * Some patients who already have a disease will be, allocated a new treatment (for example new drug or new type of surgery), and others will be allocated the standard treatment or placebo (clinical trials).
 * To study the effect of a possible preventive measure on people who do not yet have a particular disease (intervention trial).
 * A special type of intervention trial is the study of the effect of a possible intervention on whole community. For example, one (or more) community will get the intervention (e.g. water fluoridation or a vaccination programme) and other(-s) will not.

Related articles

 * Descriptive Studies
 * Analytical Studies