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 Mann-Whitney test on the data (output below) . Which of the following sentences correctly reports the results from the Mann-Whitney test?

A) People who wanted to quit smoking to improve their appearance did not significantly differ from those who wanted to quit to improve their health, U = 1415.50, z = −2.04, p = .04.
B) People who wanted to quit smoking to improve their appearance (M = 66.91) were significantly more successful at quitting than those who wanted to quit to improve their health (M = 54.09) , U = −2.04, z = 188.57, p = .04.
C) 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, U = 1415.50, z = −2.04, p = .04.
D) 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, U = 1415.50, z = −2.04, p = .04.