1. IS-171 Computing With Spreadsheets
Charts and Graphs
Week 3

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)
12/28/2018
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”
12/28/2018
Carol Wilson and Fred Ferwerda

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

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

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

9. Carol Wilson and Fred Ferwerda
Chart Types
Multiple Data Series Charts
Stacked Column Chart
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Carol Wilson and Fred Ferwerda

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

13. 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

14. 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

15. 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%
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Carol Wilson and Fred Ferwerda

16. 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

17. 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

18. 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