Range
The range is the difference between the highest and lowest scores in a distribution. The range provides limited information, because distributions in which scores bunch up toward the beginning, middle, or end of the distribution might have the same range. Of course the range is useful as a rough estimate of how a score compares with the highest and lowest in a distribution. For example, a student might find it useful to know whether he or she did near the best or the worst on an exam. The range of scores in the distribution of 20 grades in the earlier example in Table 1 would be the difference between 94 and 80, or 14. Here are the exam score data reproduced from the section on the median above.
Exam A: 23, 25, 63, 64, 67
Exam B: 23, 25, 63, 64, 98
The range for set A is 44 (67 – 23), whereas the range for set B is 75 (98 – 23).
Learning Check #9:
A memory researcher would like to know how many digits a person can recall with only one presentation of a list. She creates random lists of digits and presents them to participants. The number of digits recalled by the first 10 participants are as follows: 5, 9, 6, 10, 9, 7, 8, 7, 9, 12. What is the range of this data set?