11.50 Herbs and the common cold A recent randomized experiment of a multiherbal formula (Immumax) containing echinacea, garlic, ginseng, zinc, and vitamin C was found to improve cold symptoms in adults over a placebo group.

“At the end of the study, eight (39%) of the placebo recipients and 18 (60%) of the Immumax recipients reported that the study medication had helped improve their cold symptoms (chi-squared P@value = 0.01).” (M. Yakoot et al., International Journal of General Medicine, vol. 4, 2011, pp. 45–51).

a. Identify the response variable and the explanatory variable and their categories for the 2 * 2 contingency table that provided this particular analysis.

b. How would you explain to someone who has never studied statistics how to interpret the parenthetical part of the quoted sentence?