Random assignment or
random placement is an
experimental technique for assigning
human participants or
animal subjects to different groups in an experiment (e.g.,
a treatment group versus a control group) using , such as by a chance procedure (e.g.,
flipping a coin) or a
random number generator. This ensures that each participant or subject has an equal chance of being placed in any group. Random assignment of participants helps to ensure that any differences between and within the groups are not
systematic at the outset of the experiment. Thus, any differences between groups recorded at the end of the experiment can be more confidently attributed to the experimental procedures or treatment.