An Article That Appeared in the British Medical Journal (2010)

Multiple Choice

An article that appeared in the British Medical Journal (2010) presented the results of a randomized experiment conducted by researcher Jeremy Groves, whose objective was to determine whether the weight of his bicycle could affect his travel time to work. On each of 56 days (from mid-January to mid-July 2010) , Groves tossed a £1 coin to decide whether he would be biking to work on his carbon frame (lighter) bicycle that weighed 20.9 lbs or on his steel frame (heavier) bicycle that weighed 29.75 lbs. He then recorded the commute time (in minutes) for each trip.
Here are the summary statistics for his data:
-In terms of investigating whether the lighter carbon frame bike will tend to have a higher or lower mean commute time compared to the heavier steel frame bike, which of the following is the correct null hypothesis?

A) There is an association between the type of bike frame and commute time.
B) There is no association between the type of bike frame and commute time.
C) There is an association between days and weight of bicycle.
D) There is no association between days and weight of bicycle.