Read the following excerpt and think about how you might troubleshoot. Write your answer.

Dr. Dove was interested in the effects of chocolate on well-being. She randomly assigned 20 participants to two groups. Both groups ate as they normally would, but one group was instructed to each eats a 1-ounce square of dark chocolate after both lunch and dinner. After the participants spent four weeks on this diet, Dr. Dove asked each one to complete a questionnaire measuring well-being (happiness, contentment). However, Dr. Dove was surprised to find that the chocolate had no effect: Both groups, on average, scored the same on the well-being measure. Help Dr. Dove troubleshoot her study. What should she do next time to improve her chances of finding a significant effect on the chocolate-enhanced diet?