Question

In between-subject experiments, differences among participants are controlled chiefly through __________ and matching.

Answer 1

The correct answer is "placebos".

In between-subject experiments, groups of participants are divided between "observation" groups and "control" groups. Observation groups get administered to a particular substance which the testers want to get their effects measured. Control groups are administered the placebo and are the ones who will be used as the "reference". Any deviations from the other groups will be measured taking the control group as the reference.

Answer 2

The answer is random assignment in which is being done to participants in order to have an equivalent grouping and to be spread equally like other participants that had participated in the subject experiments in a way it is trying to promote equality.