P3.6—Graphs, charts, histograms and observation layout

Use line graphs for continuous variables, bar charts for categories and histograms for grouped frequency data.

Label axes with units, choose a scale that uses the plot area, plot accurately and only draw a best-fit line when justified.

A histogram represents continuous class intervals with touching bars, unlike a bar chart comparing named treatments.

A line joining points is not automatically a best-fit relationship, and extrapolation beyond the data needs justification.