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.