In this example, the inequality signs have been swapped so the lower number is not included in the class interval. This still works, as there are no overlaps and each number lies in a single interval.

class intervals ... based on the range of likely possible answers. For example, in a survey about the number of magazines bought by students over the space of a year, the answers given range from ...

Pitch-class sets (such as scales) can be characterized according to the inventory of possible intervals that can be formed by pairing all pitches in the set. The frequency of occurrence of various ...