## 19.6 Chapter summary

- Bar graphs are used to display data that has been collected and organised according to categories.
- Discrete data is information that is counted and can be represented by integers.
- Continuous data is collected by measuring. These data can have any value, which can change over time (so they can be represented by real numbers).
- Bar graphs are used to represent discrete data. There is usually a gap between the bars.
- A pie chart is a circle that is divided into sections. The whole pie chart represents the total amount of data.
- To make drawing pie charts easier, we can divide the circle into halves, quarters and eighths.
- A histogram is a suitable graph for representing continuous data that can be divided into intervals.
- The intervals must not overlap and must cover the entire range of the data set.
- There are no gaps between the bars of a histogram.
- Broken-line graphs are used to represent data that change continuously over time.
- Each data value is represented by a point on the graph and the points are joined by straight line segments.