Data Presentation (Cambridge (CIE) A Level Maths): Revision Note

Data Presentation

What graphs and diagrams should I be familiar with?

• You will be expected to be able to use a variety of graphs such as:

  • Stem-and-leaf diagrams

    •  Can be used with ungrouped data of a single variable

    • Shows all the data and the shape of its distribution

  • Box plots

    • Can be used with ungrouped data of a single variable

    • Shows the range, interquartile range and quartiles clearly

    • Very useful for comparing data patterns quickly

  • Cumulative frequency graphs

    • Can be used with continuous grouped data of a single variable

    • Shows the running total of the frequencies that fall below the upper bound of each class

  • Histograms

    • Can be used with continuous grouped data of a single variable

    • Can be used with varying group sizes

    • Shows the frequencies of the group, represented by the area of each bar

• You might be expected to draw a full diagram or to add to an incomplete diagram

What should I look out for when interpreting graphs?

• Look carefully at the context of the information given in the graph

• Check the scales on both axes carefully, including units

  • Sometimes the numbers will be abbreviated to fit on the scale, for example if a population is given in millions then the number 60 will represent 60 000 000

  • Look carefully at the labels and units to determine how a value should be read

• If there is more than one graph represented on the same set of axes take extra care to ensure you are reading from the correct one

• Beware of misleading graphs, the scales on the axes, units and representation can be manipulated to make a graph look more/less convincing