"Written Word Helps Wounds Heal" describes a British study: "In the study, which involved 36 people, half were asked to write about the most upsetting experience they had had, spelling out how they had felt. The rest of the study participants wrote about trival things, such as how they spent their free time. Both groups spent 20 minutes a day for three days writing. Following the writing exercise, researchers created a small skin puncture [under anesthesia] on the participants' upper arms. The wounds were examined two weeks later. It was found that the group who had written about their emotional experiences had smaller wounds, meaning they had healed more quickly. Those whose wounds were healing more slowly were found to have higher levels of stress and psychological distress."9 The sample of study participants was clearly not which one of these: a convenience sample, a volunteer sample, or a random sample?