In a parallel study design, how are participants allocated to interventions?

In a parallel study design, how are participants allocated to interventions?

• A. They are allocated to separate groups that receive different interventions concurrently
• B. They receive all interventions one after another
• C. They are randomly assigned to the same intervention
• D. They are observed without any intervention

Answer: (A)

In a parallel study design, participants are randomly allocated to separate groups, with each group receiving a different intervention at the same time. This setup lets researchers compare outcomes across interventions while they’re concurrently administered, minimizing differences due to time or sequence. It avoids carryover effects that occur when the same participant receives multiple interventions in sequence (as in crossover or sequential designs). It also isn’t observational, since an intervention is actively given, and it isn’t randomizing everyone to the same intervention, which wouldn’t provide a comparison between different treatments.

In a parallel study design, participants are randomly allocated to separate groups, with each group receiving a different intervention at the same time. This setup lets researchers compare outcomes across interventions while they’re concurrently administered, minimizing differences due to time or sequence. It avoids carryover effects that occur when the same participant receives multiple interventions in sequence (as in crossover or sequential designs). It also isn’t observational, since an intervention is actively given, and it isn’t randomizing everyone to the same intervention, which wouldn’t provide a comparison between different treatments.