IS-171 Computing With Spreadsheets Charts and Graphs Week 3

Carol Wilson and Fred Ferwerda Chart Design A chart is a graphic representation of data in an attractive, easy-to-understand form Determine the message to be conveyed Emphasis Proportional relationships Actual data Keep it simple – more is not necessarily better Understand colors (color blindness) 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Pie Chart Illustrate proportional relationships such as percentage or market share Number of slices should not exceed 6 – 7 Group small categories (% less than 5) into one category, “Other” 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Pie Chart 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types 3-D Pie Chart 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Exploded 3-D Pie Chart One or more slices are “pulled out” for emphasis 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Column Chart Vertical representation of the data 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Bar Chart Horizontal representation of the data Often preferred over a column chart – longer description labels and less crowded 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Multiple Data Series Charts Stacked Column Chart 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Chart Types Multiple Data Series Charts Side-by-Side Column Chart 12/28/2018 Carol Wilson and Fred Ferwerda

Proper Use of Graphs and Charts “A picture is worth a thousand words” When is a picture worth 1000 words? When displaying relative sizes When is a word worth 1000 pictures? Enter text ‘until done’ VisiPlot greatly increased the popularity of VisiCalc. 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda from The Visual Display of Quantitative Information, Edward Tufte, 1983 Tufte, page17 top here This chart displays 21,000 data points and 3056 counties very very well. 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Tufte, page 54 top here This chart masks the net loss in 1970. Proportionally, the middle bars BEGIN at NEGATIVE $4,200,000 from The Visual Display of Quantitative Information, Edward Tufte, 1983 12/28/2018 Carol Wilson and Fred Ferwerda

Lying with Perspective Tufte page 57 bottom This chart is terrible high lie factor (ratio of spatial change with data change) time goes from top to bottom (not standard in the west) attempt made to take perspective into account, but lost to average viewer The length of line for 18 mpg is 0.6; length of line for 27.5 mpg is 5.3 (about 9 times longer), but 27.5 mpg isn’t even *double* 18 mpg. Huge ‘lie factor’. from The Visual Display of Quantitative Information, Edward Tufte, 1983 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda from The Visual Display of Quantitative Information, Edward Tufte, 1983 Tufte, page 62 this has a high lie factor with a political intent. The data variation of 454% is depicted with a surface area variation of 4280% and a volume variation of 27,000% 12/28/2018 Carol Wilson and Fred Ferwerda

Carol Wilson and Fred Ferwerda Need Units Grauer, figure 14.4, page 176 not labeling units! Left graph represents units sold. Right graph represents dollar amount sold. Neither graph is inaccurate. Both graphs are based on the same time period. from Exploring Microsoft Excel 97, Grauer & Barber, 1998 12/28/2018 Carol Wilson and Fred Ferwerda

Dissimilar Quantities from Exploring Microsoft Excel 97, Grauer & Barber, 1998 Grauer, figure 4.15B, page 177 adding dissimilar quantities Here sales are coupled with profits. These aren’t the same animal. Better to put profits next to sales. If this were sales from one branch of company on top of other branch, that makes sense. 12/28/2018 Carol Wilson and Fred Ferwerda

Using Graphics Properly Let the graphic values/change accurately depict the data values/change Clearly label all relevant details Don’t graphically mix dissimilar elements Use the right type of graph 12/28/2018 Carol Wilson and Fred Ferwerda