How can researchers control for the fact that experimental and control groups may come to the experiment with pre-existing differences that can affect the results of the study?
A) random assignment
B) random selection
C) double-blind procedure
D) demand characteristics

Question

Quizplus · Accepted Answer

Random assignment helps to ensure that any pre-existing differences between the experimental and control groups are evenly distributed between both groups. This increases the likelihood that any observed differences between the groups at the end of the study are due to the treatment and not pre-existing differences.

How Can Researchers Control for the Fact That Experimental and Control