455-464) describes an experiment in which male athlete volunteers who were considered low caffeine consum- ers were assigned at random to one of two experimental groups. Those assigned to the caffeine...

Extracted text: 455-464) describes an experiment in which male athlete volunteers who were considered low caffeine consum- ers 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.