Imagine We Wanted to Investigate Whether the Reason for Quitting

Multiple Choice

Imagine we wanted to investigate whether the reason for quitting smoking affects success rate. We recruited a sample of 120 smokers. Half wanted to quit to improve their appearance (yellow teeth and bad breath, etc.) , and half wanted to quit to improve their health (life expectancy, etc.) . After six months we measured how successful they had been at quitting smoking. The data were skewed so we ran a Wilcoxon rank-sum test on the data (output below) . Which of the following sentences correctly reports the results from the Wilcoxon rank-sum test?

A) People who wanted to quit smoking to improve their health were significantly more successful at quitting than those who wanted to quit to improve their appearance, Ws = 3245.5, z = -2.04, p = .04.
B) People who wanted to quit smoking to improve their appearance were significantly more successful at quitting than those who wanted to quit to improve their health, T = -2.04, z = 188.57, p < .05.
C) This output relates to the Mann-Whitney test and tells us nothing about the Wilcoxon rank-sum test.
D) People who wanted to quit smoking to improve their appearance were significantly more successful at quitting than those who wanted to quit to improve their health, Ws = 3245.5, z = -2.04, p = .04.