A step graph is a special type of line graph that is made up of lines in several horizontal intervals or ‘steps’.
- The end of the previous horizontal step lies on the same vertical line for the start of the next step, i.e. each new step begins directly above where the previous step finished.
- Each horizontal step has an open circle o at the start or end point and a closed/coloured circle at the end or start point respectively.
- An open circle excludes that point from that step, whereas a closed/coloured circle includes that point in that step.
A step graph is usually used to represent situations that involve sudden jumps across intervals, such as cost of postage, car parking fees or telephone rates.
When a gap or jump appears in a graph, we say the graph is discontinuous.