SHOW ME THE NUMBERS - GBV

SHOW ME THE NUMBERSDesigning Tables and Graphs to EnlightenSECOND EDITIONSTEPHEN FEWAnalytics PressBURLINGAME, CALIFORNIA

CONTENTSPREFACE TO SECOND EDITION1.XVINTRODUCTIONThe use of tables and graphs to communicate quantitativeinformation is common practice in organizations today, yet few of ushave learned the design practices that make them effective. Thisintroductory chapter prepares the way for a journey of discovery thatwill enable you to become an exception to this unfortunate norm.PurposeScopelntended readersContent previewCommunication style2.SIMPLE STATISTICS TO GET YOU STARTED8911111215Quantitative information forms the core of what organizations mustknow to operate effectively. The current emphasis on metrics, KeyPerformance Indicators (KPis), Balanced Scorecards, and performancedashboards demonstrates the importance of numbers to organizationstoday. Stories contained in numbers can be communicated mosteffectively when we understand the fundamental characteristics andmeanings of simple statistics that are routinely used to make sense ofnumbers, as well as the fundamental principles of effectivecommunication that apply specifically to quantitative information.Quantitative relationshipsNumbers that summarizeMeasures of money3.DIFFERING ROLES OF TABLES AND GRAPHS15213539Tables and graphs are the two fundamental vehicles for presentingquantitative information. They have developed over time to the pointthat we now thoroughly understand which works best for differentcircumstances and why. This chapter introduces tables and graphsand gives simple guidelines for selecting which to use for yourparticular purpose.Quantities and categoriesChoosing the best medium of communicationTables definedWhen to use tablesGraphs definedA briet history of graphsWhen to use graphs40424344454648

X4.SHOW ME THE NUMBERSFUNDAMENTAL VARIATIONS OF TABLESTables should be structured to suit the nature of the information theyare meant to display. This chapter breaks tables down into theirfundamental variations and provides simple rules of thumb forpairing your message with the best tabular means to communicate it.Relationships in tablesVariations in table designTable design solutions5.VISUAL PERCEPTION AND GRAPHICAL COMMUNICATIONBecause graphical communication is visual, it must expressinformation in ways that human eyes can perceive and brains canunderstand. Our eyes and the parts of the brain that handle inputfrom them work in particular ways. Thanks to science, how we see isnow fairly well understood, from the initial information-carrying raysof light that enter our eyes to the interpretation of that information inthe gray folds of the visual cortex. By understanding visual perceptionand its application to the graphical communication of quantitativeinformation, you will learn what works, what doesn't, and why. Thischapter brings the principles of graphical design for communicationalive in ways that are practical and can be applied skillfully toreal-world challenges in presenting quantitative information.Mechanics of sightAttributes of preattentive processingApplying visual attributes to designGestalt principles of visual perception6.FUNDAMENTAL VARIATIONS OF GRAPHSDifferent quantitative relationships require different types of graphs.This chapter explores the fundamental variations of graphs thatcorrespond to different quantitative relationships and then pairs thesevariations with the visual components and techniques that canpresent them most effectively.Encoding data in graphsRelationships in graphsGraph design solutionsPRACTICE IN SELECTING TABLES AND GRAPHSLearning requires practice. Through practice you reinforce whatyou've learned by embedding it more securely in your memory andstrengthen your ability to make connections between the conceptswe've examined and their application to the real world.5353575961636771808787101105137

CONTENTS7.GENERAL DESIGN FOR COMMUNICATIONWith a basic understanding of visual perception, we can build a set ofvisual design principles, beginning with those that apply equally totables and graphs. Our primary visual design objectives will be topresent content to readers in a manner that highlights what'simportant, arranges it for clarity, and leads them through it in thesequence that tells the story best.HighlightOrganizelntegrate tables, graphs, and text8.TABLE DESIGNOnce you've determined that a table should be used to communicateyour message and have chosen the type of table that will work best,you should refme your design so that it can be quickly and accuratelyread and understood.Structural components of tablesTable design best practices9.141144148155155158PRACTICE IN TABLE DESIGNNothing helps learning take root like practice. You will strengthenyour developing expertise in table design by working through a fewreal-world scenarios.185GENERAL GRAPH DESIGNThe visual nature of graphs requires a number of unique designpractices. The volume and complexity of quantitative informationthat you can communicate with a single graph are astounding butonly if you recognize and avoid poor design practices that wouldundermine your story.191Maintain visual correspondence to quantityAvoid 3D10.141COMPONENT-LEVEL GRAPH DESIGNSeveral visual and textual components work together in graphs topresent quantitative information. If these components are out ofbalance or misused, the story suffers. For each component to serve itspurpose, you must understand its role and the design practices thatenable it to fulftll its role effectively.Primary data component designSecondary data component designNon-data component design191197205205224247xi

xiiSHOW ME THE NUMBERS11.DISPLAYING MANY VARIABLES AT ONCEGraphs can be used to tell complex stories. When designed well,graphs can combine a hast of data spread across multiple variables tomake a complex message accessible. When designed poorly, graphscan bury even a simple message in a cloud of visual confusion.Excellent graph design is much like excellent cooking. With a clearvision of the end result and an intimate knowledge of the ingredients,you can create something that nourishes and inspires.Combining multiple units of measureCombining graphs in a series of small multiplesOther arrangements of multi-graph series12.13.257257259268SILLY GRAPHS THAT ARE BEST FORSAKENSeveral graphs that are readily available in software fail miserably atdata presentation even though their popularity is growing. The storiesthat people attempt to tell with these graphs can be told simply andclearly using alternatives that are described in this chapter.271Donut chartsRadar chartsStacked area graphs for combining part-to-whole and time-seriesrelationshipsCircle chartsUnit chartsFunnel chartsWaterfall charts for simple part-to-whole relationships271272275277278281283PRACTICE IN GRAPH DESIGNYou've come far in your expedition into the world of graph design. It'snow time for some practice to pull together and reinforce all thatyou've learned. Expert graph design requires that you adapt and applywhat you've learned to a variety of real-world communicationproblems. Working through a few scenarios with a clear focus on theprinciples of effective graph design will strengthen your expertise andyour confidence as well.287TELLING COMPELLING STORIES WITH NUMBERSImportant stories live in the numbers that measure what's going on inthe world. Before we can present quantitative information, we mustfirst uncover and understand its stories. Once we know the stories, wecan tell them in ways that help others to understand them as well.295Characteristics of well-told statistical storiesStories in the wings297306

CONTENTS14.THE INTERPLAY OF STAN DARDS A ND IN NOVATI O N307When you design tables and graphs, you face many choices. Of theavailable alternatives, some are bad, some are good, some are best, andothers are simply a matter of preference among equally good choices.By developing and following standards for the visual display ofquantitative information, you can eliminate all but good choices onceand for all. This dramatically reduces the time it takes to producetables and graphs as well as the time required by your readers to makegood use of them. Doing this will free up time to put your creativityto use where it's most needed.APPENDICESTable and Graph Design at a GlanceRecommended Reading309309311Adjusting for Inflation313Constructing Tables Lens Displays in Excel315Constructing Box Plots in Excel318Answers to Practice in Selecting Tables and GraphsAnswers to Practice in Table Design322325Answers to Practice in Graph Design333Useful Color Palettes344IN DEX3 45xiii

xii SHOW ME THE NUMBERS 11. DISPLAYING MANY VARIABLES AT ONCE 257 Graphs can be used to tell complex stories. When designed well, graphs can combine a hast of data spread across multiple variables to make a complex message accessible. When designed poorly, graphs can bury even a simple message in a cloud of visual confusion.