Parallel randomized design
Participants are analyzed in the treatment groups they are randomly assigned to at all observations
Parallel randomized designs are the traditional type of experimental research design where study participants are randomly assigned to treatment groups and analyzed in an "intention-to-treat" fashion. "Intention-to-treat" means that participants are analyzed in the same groups to which they were randomly assigned at all observations of the outcome, regardless if they fell out of the study early or were lost to follow-up.
In parallel randomized designs, study participants are randomly assigned to treatment groups and assessed on measurements of outcomes at each observation in an experiment. In most studies, there is a baseline measurement of the outcome along with baseline demographic and prognostic measures followed by a "post" observation of the outcome variable after an intervention has been implemented in one or more of the treatment groups. A third observation of the outcome is considered a "maintenance" observation where the original effect of the treatment is tested for its stability across time, or in a dose-response fashion. Because the members of the groups stay in their group throughout the entirety of the study, they are thought to be "parallel" moving forward in time. Thus, the moniker of parallel randomized design was given to this type of experimental research design.
In parallel randomized designs, study participants are randomly assigned to treatment groups and assessed on measurements of outcomes at each observation in an experiment. In most studies, there is a baseline measurement of the outcome along with baseline demographic and prognostic measures followed by a "post" observation of the outcome variable after an intervention has been implemented in one or more of the treatment groups. A third observation of the outcome is considered a "maintenance" observation where the original effect of the treatment is tested for its stability across time, or in a dose-response fashion. Because the members of the groups stay in their group throughout the entirety of the study, they are thought to be "parallel" moving forward in time. Thus, the moniker of parallel randomized design was given to this type of experimental research design.
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