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.

Question

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.

Quizplus · Accepted Answer

The Answer of 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.

Imagine We Wanted to Investigate Whether the Reason for Quitting