Question

Which change to the investigation would remove the source of error in the dispute over the mineral supplement's effectiveness in preventing the common cold?

a) Test a fourth group, in which participants do not receive the mineral supplement.
b) Test all three groups, with each participant receiving the mineral supplement for 12 months.
c) Test only one group, with each participant receiving 200 mg/day of the mineral supplement.
d) Test only two groups, one with each participant receiving 200 mg/day and one with 50 mg/day of the mineral supplement.

Answer 1

The correct option to remove the source of error is to test a fourth group that does not receive the mineral supplement, providing a necessary control group for comparison.

Step-by-step explanation:

To assess the dispute over the mineral supplement's effectiveness in preventing the common cold, it is important to design an investigation that minimizes sources of error and allows for a clear interpretation of results. The addition of a control group (a group that does not receive the mineral supplement) is essential to any properly controlled study. In this particular question, the correct option to remove the source of error in the investigation is: a) Test a fourth group, in which participants do not receive the mineral supplement.

This option introduces a control group, making it possible to compare the incidence of the common cold in groups that received the mineral supplement with a group that did not, thereby providing a baseline measure of effectiveness.