To study the effects of noise on worker productivity, researchers have one group of subjects work in a noisy room and a second group work in a quiet room. to ensure that any differences in the productivity of the two groups actually result from the different noise levels to which the groups are exposed, the researchers would use

Random assignment.

Explanation:

Random assignment (also known as random allocation, or randomization), in psychology experiments, is randomly selecting participants or units by the use of chance procedures so that each participant or unit has the same chance (equal likelihood) of being assigned to any particular control or treatment group.

answer; analogue situations