Astudy compared the smoking cessation rates for 240 smokers randomly assigned to use a nicotine patch versus a placebo patch.

Higher smoking cessation rates were observed in the active nicotine patch group at 8 weeks (46.7% vs 20%) (P < .001) and at 1 year (27.5% vs 14.2%) (P = .011). (Hurt et al., 1994, p. 595) Therefore, rates of quitting are significantly higher using a nicotine patch than using a placebo patch after 8 weeks and after 1 year

1. What type of statistical test do you think the researchers used for this study?