Certain researchers have published peer-reviewed reports that the use of zinc lozenges reduces the length and severity of cold symptoms. What is one reason why some scientists are still skeptical about the merits of using zinc lozenges during a cold?
A) Because most people get zinc in their diet anyway, there's no reason to believe that zinc lozenges could affect a cold.
B) Previous ideas about vitamin C usage have been discredited, so there's no reason to believe new ideas about zinc lozenges.
C) There is no way of knowing if the original work was properly controlled or statistically significant.
D) There may be other reasons why the people taking zinc lozenges recovered faster, such as stress levels or differences in their immune systems.

Question

Quizplus · Accepted Answer

Some scientists may be skeptical of the merits of using zinc lozenges during a cold because there may be other factors, such as stress levels or differences in immune systems, that contributed to the faster recovery of the group taking zinc lozenges. It is important to control for these factors to ensure that the benefits observed are indeed due to the zinc.

Certain Researchers Have Published Peer-Reviewed Reports That the Use of Zinc