Range and Interquartile Range
Suppose a new teacher is going to teach fourth grade next year and is offered a choice between two classes, both of which are very similar in terms of average scores obtained on a standardized test. Before making a choice, the teacher would be wise to ask about the variability. He or she might learn, for instance, that one class has little variability (the students’ scores are all very close to their average), while the other has tremendous variability (the students’ scores vary from the highest to the lowest possible with a great deal of spread in between). Which class should the teacher choose? There is no right or wrong answer to the question, but clearly information on variability would be important in helping to make a decision.