A recent randomized experiment of a multi-herbal 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).”
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?