To test an herbal treatment for depression, 100 volunteers who
suffered from mild depression were randomly divided into two
groups. Each person was given a month's supply of tea bags. For one
group, the tea contained the herb mixed with spice tea, whereas for
the other group, the bags contained only the spice tea.
Participants were not told which type of tea they had, and were
asked to drink one cup of tea per day for a month. At the end of
the month, a psychologist evaluated them to determine if their mood
had improved. The psychologist did not know which of the subjects
had the tea with the herbal ingredient added. Which of the
following statements is true regarding this study? Check all that
apply.
The "only spice tea" group serves as the control group.
This study is an observational study.
This study is double-blind.