Random Assignment

Random assignment is the process by which researchers select individuals from their total sample to participate in a specific condition or group, such that each participant has a specifiable probability of being assigned to each of the groups or conditions. These different conditions or groups represent different levels of the independent variable. Random assignment is generally considered the most important criterion to qualify a research design as a truly experimental design. A well-known example of random assignment is the randomized clinical trial, such as the 2020 COVID-19 vaccine trials. In these randomized clinical trials, researchers randomly assigned some participants to receive either the real vaccine to be evaluated or a [Page 1346]placebo vaccine (a sterile saltwater substance that appears identical to the vaccine but is ...