Cumulative Frequency
Cumulative frequency is the running total of frequencies in a data set. It is calculated by adding each frequency from a frequency distribution table to the sum of its predecessors, representing the total number of observations that fall below a certain value or class boundary.
Example
For a data set of quiz scores with consecutive frequencies $f_1 = 3$, $f_2 = 5$, and $f_3 = 2$, the cumulative frequencies ($cf$) are:
- First class: $cf_1 = 3$
- Second class: $cf_2 = 3 + 5 = 8$
- Third class: $cf_3 = 8 + 2 = 10$