Answer:
To reduce systematic error.
Step-by-step explanation:
The researchers would have used random allocation in order to decreases systematic error in the experiment. If we don't apply random allocation to the experiment, there is high chances of systematic error in the experiment and the result is not of high quality. Independent variables is a type of variable whose variation does not depend on another factor while on the other hand, dependent variables is a type of variable whose variation depend on another factor.