13.12 Chapter Review
13.12.1 Chapter summary
Professional visual communication begins with the comparison the audience must make. The design should use accurate encodings, informative titles, deliberate emphasis, readable labels, appropriate uncertainty, accessible colour and structure, and enough context to prevent a technically correct display from becoming misleading.
13.12.2 Common mistakes
- choosing a chart type before identifying the intended comparison;
- using area, volume, or decorative effects that distort magnitude;
- removing labels, baselines, denominators, or uncertainty needed for interpretation;
- using colour as the only way to distinguish important categories; and
- building dashboards around available fields rather than user decisions.
13.12.4 Exercises
Exercise 1. Choose the most appropriate primary display for each task: comparing retention across four acquisition channels, showing monthly visits for three years, reporting exact facility capacity and wait-list counts, and examining the relationship between first-month visits and twelve-month retention.
Check Your Work
Use a bar or dot plot for retention by channel, a line chart for monthly visits, a concise table for exact capacity and wait-list values, and a grouped retention or probability plot for the relationship between early visits and a binary retention outcome.
Exercise 2. Create one excellent table and one excellent chart from retention_by_facility.csv. Give each an explanatory title and a note defining the denominator.
One Possible Answer
The table should show facility, eligible members, retained members, and retention rate sorted meaningfully. A suitable chart is a horizontal dot plot of retention rate with a common percentage scale. A message title might note that North Ridge has the lowest observed retention. The note should define eligible members and explain that censored periods are excluded.
Exercise 3. Redesign the monthly visit figure for an audience interested primarily in North Ridge. Preserve the comparison with other facilities without making them visually dominant.
One Possible Answer
Use one saturated, accessible colour and a slightly heavier line for North Ridge. Show the other facilities in thin neutral grey, keep a common axis, directly label North Ridge, and use a title that states its relevant pattern. Do not delete the comparison series or use separate scales.
Exercise 4. Conduct an accessibility audit of your figure. Check colour dependence, contrast, text size, reading order, alternative text, and whether the main conclusion remains visible in grayscale.
Check Your Work
The figure should not depend on colour alone, should meet readable contrast and text-size expectations, and should preserve a logical title-to-chart-to-note reading order. Alternative text should state the chart’s purpose and principal comparison. A grayscale check should leave the highlighted series and conclusion distinguishable through line weight, labels, symbols, or position.