3.5 Practical Advice and Potential Problems

3.5.1 Features of Good Graphs

Statistical software has become quite sophisticated in giving users high-quality graphs with ease. Still, a few customization steps can improve a graphical representation. The goal of customization is to produce more effective graphs. What are some useful guidelines on constructing a graph? A good graph is self-contained. This means that everything on the graph should be explained:

• All the axes should be labeled in understandable terms.

• Marker symbols should be clearly identified.

• Smoother lines and connecting lines should be recognizable throughout the range of the graph.

• Marker symbols identifying subgroups of data should clearly differentiate between subgroups.

• Axes scales and tick spacing should facilitate comparisons with other graphs.

• Annotations on the graph should be helpful for interpretation. Unhelpful annotations, sometimes referred to as chart junk, should be avoided.