In a follow-up study, 103 patients in the Netherlands having warts were randomly assigned to use duct tape or a placebo, which was a ring covered by tape so that the wart itself was kept clear (Arch. Pediat. Adoles. Med. 2006; 160: 1121–1125).
a. Identify the response variable, the explanatory variable, the experimental units, and the treatments.
b. After six weeks, the warts had disappeared for 16% of the duct tape group and 6% of the placebo group. However, the difference was declared to be “not statistically significant.” Explain what this means.