EXAMPLE 9 The rise in college education

Figure 10.11 shows the rise in the percentage of women aged 25 years and over who have at least a bachelor’s degree. There are only five data points, so a line graph should be simple. Figure 10.11 isn’t simple. The artist couldn’t resist a nice background sketch and also cluttered the graph with grid lines. We find it harder than it should be to see the data. Using pictures of the female graduate at each time point distorts the values in the same way as a pictogram. Grid lines on a graph serve no purpose—if your audience must know the actual numbers, give them a table along with the graph. A good graph uses no more ink than is needed to present the data clearly. In statistical graphics, decoration is always a distraction from the data, and sometimes an actual distortion of the data.