Suppose that experiment to see if taking vitamin C, vitamin D, or both, help prevent or reduce cold symptoms was conducted based on a random sample of 1981 individuals. Subjects were assigned to receive vitamin C only, vitamin D only, vitamin C § and D, or placebo, and then were monitored for the duration of the cold season to see if they developed a cold or not. The § results were tabulated in a two-way table in which the column variables were the vitamin supplements and the row variables were the cold responses. Researchers then conducted a chi-square test for independence to see if cold responses and vitamin supplements are dependent. How many degrees of freedom does the chi-square statistic have? Degrees of freedom?