Question: Explain which of the "difficulties and disasters" is most likely to be a problem in each of the following experiments, and why:
a. To see if eating just before going to bed causes nightmares, volunteers are recruited to spend the night in a sleep laboratory. They are randomly assigned to be given a meal before bed or not. Numbers of nightmares are recorded and compared for the two groups.
b. A company wants to know if placing green plants in workers' offices will help reduce stress. Employees are randomly chosen to participate, and plants are delivered to their offices. One week later, all employees are given a stress questionnaire and those who received plants are compared with those who did not.