1. The teacher noticed that some students reported feeling more motivated when revising in groups. She decided to conduct an experiment to compare group revision and solo revision.

Twenty A Level psychology students from the school took part in the study. They were randomly allocated to one of two conditions:

• Condition A: revise alone for 15 minutes

• Condition B: revise in groups of 3 or 4 for 15 minutes

All students revised the same set of psychology terms. After the revision period, all students completed a 20-mark test on the material. The teacher recorded each student’s score.

Table 1: Mean score on the 20-mark psychology test and the range for each condition

What do the mean and range values in Table 1 suggest about students’ test performance after revising alone compared with revising in groups? Justify your answer.