2.6: 累积频率分布

A cumulative frequency distribution is another type of frequency distribution. Instead of reporting how many data values fall in some classes, it reports how many data values are contained in either that class or any class to its left. Technically, it means the sum of frequencies of the class and all the classes below it in a frequency distribution. A cumulative frequency is calculated by adding the frequency of each class lower than the corresponding class interval or category. In general, a cumulative frequency doesn’t have to include everything less than something. The cumulative frequency distribution table calculators save a lot of time when tabulating the data. It makes calculations easier and leads to the organization of data in seconds.