1
How did you ever do without it?
- from the first VisiCalc ad, 1979
© Keith Vander Linden, 2005
2
Accountant’s Paper Ledger
2-Dimensional representation of
accounting data
image from Grauer&Barber, Excel 2003, Prentice Hall, Oct., 2004
© Keith Vander Linden, 2005
3
Dan Bricklin (1951-)
VisiCalc
●
●
●
●
1979
Visible, interactive
accountants ledger
Developed for the
Apple II
A “killer” business
application for the
personal computer
images from www.bricklin.com, Oct., 2004
© Keith Vander Linden, 2005
6
“What if?”
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●
The biggest advantage a spreadsheet has
is the ability to ask the “what if?” questions
(and get a quick answer).
Be very, very lazy (in the long run):
–
Use equations to compute answers as much
as possible.
– “What if” questions answered by tweaking the
data.
© Keith Vander Linden, 2005
7
Spreadsheet Cells
●
●
Worksheets are 2-dimensional arrays of cells.
Each cell is referred to by its cell reference.
–
●
Examples: A1, E10, AZ1024
Cells can be grouped as a range.
–
Examples: A1:E10, C5:Q8
© Keith Vander Linden, 2005
8
Spreadsheet Values
●
Constants/literals
–
A number
– A text label
●
Formulas (always begins with an =)
–
Numbers
– Arithmetic (+, -, *, /)
– Functions
●
Worksheet contents are updated in real time.
© Keith Vander Linden, 2005
9
Be Very, Very Lazy
●
This usually means doing some work up
front.
Can easily ask “what if?”
– Compute correct answers.
–
●
Guidelines
–
No numbers in formulas.
– sum() and average() should refer to
ranges.
© Keith Vander Linden, 2005
10
Relative/Absolute Addressing
●
When cells are copied:
–
relative addresses are modified
automatically
– absolute addresses always refer to the
same cell
●
Syntax:
Relative address: A1
– Absolute address: $A$1
–
●
Use the F4 key!!
© Keith Vander Linden, 2005
13
Spreadsheet Issues
●
Powerful tools can create powerful
problems.
© Keith Vander Linden, 2005
14
Technology and Humanity
What’s the
Big Idea
●
Working with technology can be
dehumanizing.
●
“Be fruitful and increase in number; fill the
earth and subdue it.” - Genesis 1:28
© Keith Vander Linden, 2005
15
Graphs and Charts
●
Quantitative data can frequently be
illustrated in a compelling way using charts
and graphs.
●
Spreadsheet systems usually provide
graphing and charting capabilities.
Here are some examples.
●
© Keith Vander Linden, 2005
© Keith Vander Linden, 2005
© Keith Vander Linden, 2005
18
image from VDQI, 1983
© Keith Vander Linden, 2005
19
Chart Types
Calvin Expenditures, 2003-2004
●
Pie charts
Financial
Other, $23.5 Aid, $20.8
Food, $6.0
Salaries, $35.3
Benefits,
$15.6
2004 Election Voting Percentages - Michigan
60%
Column/bar charts
40%
Percentage
●
51%
48%
50%
30%
20%
10%
1%
0%
0%
0%
0%
Nader
Badnarik
Cobb
Peroutka
Brown
0%
Bush
Kerry
Candidate
Line charts
4,400
4,300
4,200
4,100
4,000
3,900
3,800
3,700
Enrollment
●
College Enrollments
Year
●
Maps
© Keith Vander Linden, 2005
20
Graph/Chart Issues
●
Data values can, however, be obscured or
misrepresented using charts.
●
Here are some examples.
© Keith Vander Linden, 2005
© Keith Vander Linden, 2005
© Keith Vander Linden, 2005
23
image from VDQI, 1983
© Keith Vander Linden, 2005
25
image from VDQI, 1983
© Keith Vander Linden, 2005
26
Edward Tufte (1940-)
VDQI, 1983
Lying graphics cheapen the
graphical art everywhere …
When a chart on television
lies, it lies millions of times
over; when a New York
Times chart lies, it lies
900,000 times over to a great
many important and influential
readers. VDQI, p. 53-79
images from www.edwardtufte.com, Oct., 2004
© Keith Vander Linden, 2005
27
from Calvin College Chimes, Oct. 6, 2000
© Keith Vander Linden, 2005
28
from Calvin College Chimes, Sept. 29, 2000
© Keith Vander Linden, 2005
29
Wheaton
25%
Calvin
20%
Hope
25%
Kalamazoo
30%
image from Exploring Microsoft Excel 97, Grauer & Barber, 1998
© Keith Vander Linden, 2005
30
Amount
MyCompany.com
$45
$40
$35
$30
$25
$20
$15
$10
$5
$0
profit
sales
2002
2003
2004
2005
Year
image from Exploring Microsoft Excel 97, Grauer & Barber, 1998
© Keith Vander Linden, 2005
31
Using Charts/Graphs Properly
●
●
Decide what you want to present.
Present it accurately and unambiguously.
–
–
–
–
–
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.
Don’t add “chartjunk”.
© Keith Vander Linden, 2005
32
Technology and Lying
What’s the
Big Idea
●
It is as easy to lie or mislead with
technology.
●
“When he lies, he speaks his native
language, for he is a liar and the father of
lies.” - John 8:44
© Keith Vander Linden, 2005