The paper “ Effects of Caffeine on Repeated Sprint Ability, Reactive Agility Time, Sleep and Next Day Performance” (Journal of Sports Medicine and Physical Fitness [ 2010]: 455– 464) describes an experiment in which male athlete volunteers who were considered low caffeine consumers were assigned at random to one of two experimental groups. Those assigned to the caffeine group drank a beverage which contained caffeine 1 hour before an exercise session. Those in the no- caffeine group drank a beverage that did not contain caffeine 1 hour before an exercise session. That night, participants wore a device that measures sleep activity. The researchers reported that there was no significant difference in mean sleep duration for the two experimental groups. In the context of this experiment, explain what it means to say that there is no significant difference in the group means. In particular, explain if this means that the mean sleep durations for the two groups are equal.