MATH 3400 Computer Applications of Statistics Lecture 6 Data Visualization and Presentation

Management Problem-Solving Scenario Scenario: You have to create a professional presentation for your client – can you do it? Do you know what NOT to do?

Challenger Disaster January 28, 1986 the Challenger Space Shuttle exploded killing 7 astronauts. Direct cause was the faulty seal of 2 rubber “O” rings. The indirect cause of the tragedy was poor data presentation.

Data Presentation Edward Tufte is considered the authority on the Visual Display of Quantitative Information. Some of his thoughts -  Clear and intelligent design not only reflects, but also spurs clear and intelligent thought.  Clutter and confusion are failures of design, not attributes of the information.  Bad graphics fail because they omit or manipulate context, deceive by discouraging comparison or obscuring important details.

Membership Mix Analysis – Projected Financial Impact Projected monthly dues will decrease over time - This graph manipulates the audience!

Membership Mix Analysis – Projected Financial Impact Projected monthly dues will decrease over time - This graph communicates the same information, but does not manipulate!

Membership Mix Analysis – Projected Financial Impact What the heck is this?

This graph is counterintuitive…

Please never do this…

Data Presentation Most data that you will be asked to present will be represented by one of the following: Line Graphs Column Graphs Bar Graphs Pie Graphs Regarding graphs – the graph should instantly communicate the message. Within presentations, graphs are generally displayed for 15 seconds. Therefore, the graph should be simple (no 3D!), and the data legible.

Data Presentation The line graph is the most common graph used to display data. The line graph should be used to communicate trends over time. If negative values need to be communicated, the line should fall below the x axis. Don’t use red unless the figures are negative.

Data Presentation Column Graphs highlight specific amounts for specific periods of time. The focus is on the quantity rather than the trend. As with line graph, if the values are negative, the values should fall below the x axis.

Data Presentation Bar Graphs focus on quantities of particular items. No time element. NOT a column graph on its side. Most underutilized graph.

Data Presentation Pie Charts show relationships of each part to the whole. Use sparingly. VERY rarely used in academia. Don’t use if more than 4 wedges. “…the only thing worse than a pie chart is several pie charts…” - Tufte

Data Presentation For more than four categories, use a table rather than a pie chart. NorcrossDallasChicagoAtlanta 2000 Units Produced Units Produced

Graph Components The Title –Use one or at most 2 lines. –Main Title should either be in ALL CAPS or in upper and lower case in bold. –Subtitle should be in smaller (but same) font. –Use Black or Blue.

Graph Components  Vertical Axis –Scale is the key –If 0 is not the lowest point on your graph, point this out to the audience. (This is one way to manipulate data) –Your scale should only go as high as necessary to contain the data. –Ensure that the units are labeled. –Never label a vertical axis vertically.

What the manager of the Dallas Plant might show to Senior Management…

What the manager of the Norcross Plant might show to Senior Management…

What should be shown…

Graph Components  Horizontal Axis Normally indicates time, or the independent variable. Ensure that the axis is labeled. Again, scale is the key.

GMAT scores go down with age… What is wrong with this graph?

Graph Components  Tick Marks and Grid Lines Use Sparingly – they can make the graph look too busy. Decrease the color (use gray rather than black). Err on the side of too few rather than too many.

Comparison of Tick Marks…

Conventions of Visual Design* Audiences read visuals from left to right Audiences read visuals from top to bottom Audiences read visuals from center to periphery Audiences assume that the items in the foreground are more important than items in the background. Audiences assume that large things are more important than small things Audiences assume that thick things are more important than thin things. Audiences assume that things with the same size, shape, color are related. Audiences assume that an item is important if it contrasts with the surroundings. Leslie S. Olsen and Thomas H. Huckin, Principles of Communication for Science and Technology (New York, McGraw Hill Book Co., 1983) (pg )

Guidelines for Using Color Less is Better! If in doubt, use black. Use color to – –Emphasize –Differentiate the data –Differentiate you (e.g., UPS=Brown…Home Depot=Orange) Generally, Black and Blue are used for Titles and Text. Red usually indicates a negative situation.

Guidelines for using color  Are members of your audience colorblind?  8% of all men and.5% of all women are colorblind  Colorblind people have difficulty seeing the following combinations: Red and green Red, brown and green Green, brown and gray Red and black Light blue and purple Pastels

Guidelines for using color If you cannot change the colors you have chosen, incorporate a simple pattern…