A group of college students believes that herbal tea has remarkable restorative powers. To test its theory, the group makes weekly visits to a local nursing home, visiting with residents, talking with them, and serving them herbal tea. After several months, many of the residents are more cheerful and healthy.

1. The lurking variable in this experiment is

a. visits of the college students.
b. the fact that this is a local nursing home.
c. herbal tea.
d. the emotional state of the residents.

2. The explanatory variable in this experiment is

a. visits of the college students.
b. herbal tea.
c. the emotional state of the residents.
d. the fact that this is a local nursing home.

3. Which of the following may be correctly concluded from this study?

a. The results of the study are not convincing because only a local nursing home was used and only for a few months.
b. Herbal tea does improve one's emotional state, at least for the residents of nursing homes.
c. There is some evidence that herbal tea may improve one's emotional state. The results would be completely convincing if a scientist had conducted the study rather than a group of college students.
d. The results of the study are not convincing because the effect of herbal tea is confounded with several other factors.