The goal of the experimental research strategy is to establish the existence
of a cause-and-effect relationship between two variables. Note that it is possible
for two variables to be related, yet the relationship is merely coincidental.
For example, in a group of children who are 6 to 12 years old, there will be a
strong relationship between the children’s weights and their mathematics
ability; as weight increases from child to child, ability also tends to increase.