The range is the difference between the minimum and maximum values in a list of numbers.
If you have a list of numbers there are several indicators to describe this list. A very easy indicator is the range. The range is - by definition - the difference between the highest value and the lowest value. So, all you need to do is to find the highest value and the lowest value and subtract the lowest value from the highest.
For instance in the list 11, 11, 13, 14 and 18 the range is (18 – 11 =) 7.
And in the list 111, 111, 113, 114 and 118 the range is (118 – 111) = 7.
Is the range an important indicator?
Yes and no. The range of a list should always be compared with the ranges in other lists. Suppose you do a research with students and in a questionnaire you ask the respondents to fill in their age. In one group you might find a range of (18 to 25 is) 7 and in another group you find a range of (18 to 56 is) 38. Now you can state that these groups aren’t very well comparable due to a big difference in range.
If this is the case in your research, you should look more closely at your data. Maybe there is an easy way to make the groups more similar. What should be done is difficult to tell without looking closer. The range is only a quick and simple indicator to see if the groups differ substantially.