Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and here for more.

Cumulative Frequency Distribution

Sometimes, one wants to know how often an event occurs below or above a threshold value. For example, how many women are taller than 177 cm. While this can be calculated by integrating the density distribution, it is more convenient to use an integrated version of the density distribution (the cumulative frequency distribution). In order to see the difference, first take a look at the distribution of the body height of women in a small European city:

While determining the percentage of women taller than 177 cm means integrating the frequency distribution (left figure, red area), the same number can be obtained from the cumulative frequency distribution (right) by simply setting a threshold value.

If you are not sure how the cumulative frequency distribution is calculated, you may want to have a look at the following  interactive example .