The article "When Your Hair's a Real Mess, Your Self-Esteem Is Much Less" describes a study wherein participants "were divided into three groups. One group was questioned about times in their lives when they had bad hair. The second group was told to think about bad product packaging, like leaky containers, to get them in a negative mindset. The third group was not asked to think about anything negative. All three groups then underwent basic psychological tests of self esteem and selfjudgment. The people who pondered their bad-hair days showed lower self-esteem than those who thought about something else."27
a. Was this an observational study, an experiment, or a sample survey?
b. Which group was included to see if thoughts about bad hair are worse for people's self-esteem than other negative thoughts-the second or third group?
c. Which is more important: obtaining a random sample of participants for the study, or randomly assigning participants to one of the three groups?
d. Which of these is most problematic in attempting to use the study's results to conclude that people having "bad hair days" suffer from low self-esteem: placebo effect, experimenter effect, lack of realism, non-compliance, or imposing a treatment that is unethical?