Final answer:
The purpose of random assignment is to minimize differences in participants' characteristics across all conditions of an experiment.
Step-by-step explanation:
The purpose of random assignment is to minimize differences in participants' characteristics across all conditions of an experiment. Random assignment is critical for sound experimental design as it makes it unlikely that there are systematic differences between the groups. By randomly assigning participants, we can assume that any differences observed between experimental and control groups result from the manipulation of the independent variable.