The final graph we shall look at in this section is the ogive. This is a way of plotting the cumulative frequency of occurrences. The cumulative frequency is like a running total of all events as they occur, and it is often found on a tally chart.
Let's look at an example.
| Problem | Frequency | Cumulative Frequency |
|---|---|---|
| Colour ran at first wearing | 2 | 2 |
| Don't like them | 2 | 4 |
| Heel fell off | 7 | 11 |
| Lining disintegrated | 8 | 19 |
| Odd sizes in a box | 4 | 23 |
| Too tight | 3 | 26 |
| Trim fell off | 12 | 38 |
| Wrong colour for outfit | 3 | 41 |
This information can be represented graphically by means of an ogive (an architectural term for the rib of a vault). Pareto charts, as you will see in the next section, are often completed by adding an ogive showing either the cumulative frequency or the cumulative percentage for the defect categories.