MCO 7400 Module 4 Redesigning Charts for a Transit Board Example

A Fourteen-Slice Pie and an Axis at 80 Percent: Redesigning a Transit Board's Charts

Student Name

Master of Business Administration, Thomas Edison State University

MCO-7400: Management Communications

Mentor Name

Month Day, Year

A Fourteen-Slice Pie and an Axis at 80 Percent: Redesigning a Transit Board's Charts

Purpose

This report reviews the three charts in the monthly board packet of Tri-County Regional Transit, a composite bus agency serving a mid-sized metropolitan area, and recommends redesigns. Board members use the packet to decide where to add service and how to judge the agency's performance, so a misleading or unreadable chart can lead to a poor decision. The review applies principles for presenting information drawn from perception research (Kosslyn, 2007) and research on how accurately people read different kinds of graphs.

Standards for Accurate Graphics

Kosslyn (2007) grounds his advice in how perception and memory work and organizes it into eight principles: relevance, appropriate knowledge, salience, discriminability, perceptual organization, compatibility, informative changes and capacity limitations. Three matter most here. Under the principle of capacity limitations, people can hold only about four groups of information in mind at once. Under discriminability, marks must differ enough to be told apart. Under compatibility, the form of a display should match its meaning, so bigger values should look bigger in proportion.

Cleveland and McGill (1984) supplied experimental evidence on which visual encodings people judge most accurately. Judgments of position along a common scale were the most accurate, followed by position on separate but aligned scales, then length, then angle and slope, with area, volume and color judged least accurately. Clampitt (2016) frames the managerial point: visual communication is persuasive, and with that power comes a duty not to mislead.

Chart 1: Ridership by Route

The packet shows ridership for the agency's 14 routes as a three-dimensional pie chart with a legend. The chart violates capacity limitations, since 14 slices exceed what a reader can compare; discriminability, since several slices of 4 to 6 percent are indistinguishable; and compatibility, since the three-dimensional tilt makes front slices look larger than back slices of equal size. It relies on angle and area, the least accurate judgments in Cleveland and McGill's ranking.

Redesign: a horizontal bar chart sorted from highest to lowest ridership, with route names on the bars and values printed at their ends. The four busiest routes, which carry 58 percent of riders, can be shaded darker to satisfy the salience principle and focus the board's attention where service decisions matter most.

Chart 2: On-Time Performance

On-time performance by quarter appears as a vertical bar chart whose axis begins at 80 percent. A rise from 84 to 87 percent therefore looks like a near doubling in bar height, violating compatibility. Bars encode length from a baseline, so truncating the baseline distorts the very judgment the bars invite.

Redesign: a dot plot or line chart, which encodes position rather than length and can legitimately use a narrower scale, with the axis clearly labeled, the agency's 85 percent target shown as a reference line and each value printed. The redesign shows the real improvement, three points, and whether it crosses the target, which is the board's actual question.

Chart 3: Fares and Ridership

The third chart plots monthly fare revenue and ridership as two lines on separate left and right axes. Because each axis can be scaled independently, the lines can be made to cross or diverge at will, and readers tend to infer relationships the data may not support.

Redesign: two small charts stacked vertically with a shared time axis, one for ridership and one for revenue, each with its own clearly labeled scale. Small multiples let readers compare timing without implying that the two series are measured on comparable scales.

Summary of Redesigns

The changes can be summarized for the board's staff.

Recommendations and Trade-offs

The agency should adopt the three redesigns in next month's packet and issue a one-page chart standard for staff: no three-dimensional effects, bars always start at zero, no more than about four highlighted categories, values labeled where precision matters and every chart titled with its main finding. The trade-off is that some board members are used to the old formats and may initially find the new charts less familiar, and staff will spend a few hours rebuilding templates. A brief note introducing the new charts in the next packet would ease the change.

Testing the Redesigns

Before the new charts replace the old ones, staff should test them with two or three board members. Each reader can be asked what the chart says in one sentence and how long it took to see it. If readers of the old pie chart cannot name the third-busiest route while readers of the sorted bars can, the redesign has done its job. The same test can be used for any future chart, and it costs only a few minutes.

Conclusion

Each chart in the current packet asks the board to make the least accurate visual judgments, comparing angles, areas and distorted lengths. Redesigns based on Kosslyn's principles and Cleveland and McGill's findings let the board see what the data actually show, which is the point of a chart in a management report.

References

Clampitt, P. G. (2016). Communicating for managerial effectiveness: Challenges, strategies, solutions (6th ed.). SAGE.

Cleveland, W. S., & McGill, R. (1984). Graphical perception: Theory, experimentation, and application to the development of graphical methods. Journal of the American Statistical Association, 79(387), 531-554. https://doi.org/10.1080/01621459.1984.10478080

Kosslyn, S. M. (2007). Clear and to the point: 8 psychological principles for compelling PowerPoint presentations. Oxford University Press.