7.21 The return-trip effect.
We often feel that the return trip from a destination takes less time than the trip to the destination even though the distance traveled is usually identical. To better understand this effect, a group of researchers ran a series of experiments.9 In one experiment, they surveyed 69 participants who had just returned from a day trip by bus. Each was asked to rate how long the return trip had taken, compared with the initial trip, on an 11-point scale from a lot shorter to a lot longer. The sample mean was −0.55, and the sample standard deviation was 2.16.
7.21
(a) Because , we can still use the t procedure for non-Normal distributions. (b) . The data are significant at the 5% level; there is evidence that the mean rating is different from zero. (People do not feel that the trips take the same time.)