ORI Curriculum Examples




Case example for Random Assignment

Definition : Random assignment is a procedure used in experiments to create study groups with similar characteristics so that the groups are equivalent at the beginning of the study.

In a study to help individuals quit smoking, investigators randomly assigned participants to one of two groups. In Group A, participants took a class to quit smoking. The classes took place each week for 10-weeks and included information about the benefits of quitting smoking. In addition, participants in the class received strong social support from mentors or "buddies." In the Group B, participants read a 3-page pamphlet created by the American Cancer Association that explains the benefits of quitting smoking. The investigator randomly assigned participants to one of the two groups. It was found that those who participated in the class and received support from their buddies were more likely to quit smoking compared to those in the other group that received only the pamphlet.

Discussion questions

1. Why do you think random assignment was used in this study?

2. What would happen if the participants were allowed to choose their own group? What if the same results were found as in the case where individuals were randomly assigned?

3. If the participants could choose their own group, would the researchers feel as confident about the results as they would if random assignment were used? Why or why not?