1. IS-171 Computing With Spreadsheets
Charts and Graphs
Week 4

2. 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)
1/17/2019
Carol Wilson and Fred Ferwerda

3. 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”
1/17/2019
Carol Wilson and Fred Ferwerda

4. Carol Wilson and Fred Ferwerda
Chart Types
Pie Chart
1/17/2019
Carol Wilson and Fred Ferwerda

5. Carol Wilson and Fred Ferwerda
Chart Types
3-D Pie Chart
1/17/2019
Carol Wilson and Fred Ferwerda

6. Carol Wilson and Fred Ferwerda
Chart Types
Exploded 3-D Pie Chart
One or more slices are “pulled out” for emphasis
1/17/2019
Carol Wilson and Fred Ferwerda

7. Carol Wilson and Fred Ferwerda
Chart Types
Column Chart
Vertical representation of the data
1/17/2019
Carol Wilson and Fred Ferwerda

8. 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
1/17/2019
Carol Wilson and Fred Ferwerda

9. Carol Wilson and Fred Ferwerda
Chart Types
Multiple Data Series Charts
Stacked Column Chart
1/17/2019
Carol Wilson and Fred Ferwerda

10. Carol Wilson and Fred Ferwerda
Chart Types
Multiple Data Series Charts
Side-by-Side Column Chart
1/17/2019
Carol Wilson and Fred Ferwerda

11. 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.
1/17/2019
Carol Wilson and Fred Ferwerda

12. 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.
1/17/2019
Carol Wilson and Fred Ferwerda

13. 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
1/17/2019
Carol Wilson and Fred Ferwerda

14. 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
1/17/2019
Carol Wilson and Fred Ferwerda

15. 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
1/17/2019
Carol Wilson and Fred Ferwerda