Histograms

Grouped frequency distribution Shows how many values of each variable lie in a class. Some information is lost. When presenting this information in a histogram we must first decide on class boundaries.

Class boundaries ≤ h < ≤ h < ≤ h < ≤ m < ≤ m < ≤ m < ≤ a < ≤ a < ≤ a < 26

Some special cases

Histograms

Frequency density

Histograms A bar chart is a histogram if: the bars have no spaces between them (spaces are just bars of zero height), and the area of each bar is proportional to the frequency.

Example 1

Example 2 Do Q1, Q5, Q6, Q8, pp

Cumulative frequency diagrams An alternative method of depicting continuous data is a cumulative frequency graph. Cumulative frequencies are plotted against the upper class boundaries of the corresponding class. Such graphs can be used to read of other information e.g. percentage estimates of how much of the sample has a certain characteristic.

Example Do Q5, Q6 p.19 Do Misc. Exercises pp