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04/18/23 BUS304 – Data Presentation 1
Graphs
Visual presentation of data
Pie Chart
Bar Chart
Line Chart
Scatter Chart
04/18/23 BUS304 – Data Presentation 2
A good graph should
Accurately conveys the information
Grabs the reader’s attention (visually enjoyable)
Complements or demonstrates arguments presented in the text
Is simple and uncluttered
Clearly shows trends or differences in the data
Is visually accurate (i.e. one chart value is 15 and another is 30,
then 30 should be twice the size of 15)
04/18/23 BUS304 – Data Presentation 3
Average Gas Prices from 1999-2002
$0.00
$0.20
$0.40
$0.60
$0.80
$1.00
$1.20
$1.40
$1.60
1999 2000 2001 2002
Year
Pric
e P
er G
allo
n
Average Unleaded Price
Average Premium Price
04/18/23 BUS304 – Data Presentation 4
No. of People that have each investment
Mutual Fund22%
Savings Account
31%Certificate of
Deposit9%
Individual Stocks21%
Bonds5%
Real Estate10%
Other2%
04/18/23 BUS304 – Data Presentation 5
Why use graphs?
Graphs
Are quick and direct
Highlight the most important facts
Facilitate understanding of the data
Can convince readers
Can be easily remembered.Most of the time, creating graphs is more of an art. Both visually correct data can create different
Most of the time, creating graphs is more of an art. Both visually correct data can create different
04/18/23 BUS304 – Data Presentation 6
Not always good to use graphs
The data are very dispersed The data are very numerous
04/18/23 BUS304 – Data Presentation 7
Not always good to use graphs
There are too few data The data show little variations
Sometimes, you may need to try different graphs, and may determine not to use graph in the end.
Sometimes, you may need to try different graphs, and may determine not to use graph in the end.
04/18/23 BUS304 – Data Presentation 8
Bar Charts Horizontal bars or vertical bars (also called “columns” in Excel)
Used to represent categorical data Each bar (column) represents one category
The width (height) of the bar represents the number in the category
Horizontal bar chart provides more space for category names
Vertical bar shows a clearer trend when representing yearly data
0 10 20 30 40 50 60
1993
1994
1995
1996
1997
1998
0
10
20
30
40
50
60
1993 1994 1995 1996 1997 1998
04/18/23 BUS304 – Data Presentation 9
Create a basic bar chart Open file “data2.xls” Create two bar charts using the data in Data Sheets
“Column Chart” and “Bar Chart”
04/18/23 BUS304 – Data Presentation 10
Other Bar Charts
Side by side bars / stacked bars / 100% stacked bars when more than one piece of info in one category
Create these three charts using data from worksheet Side-by-side. Write down, for each chart, the primary information the chart conveys.
Legend is important in those charts
Legend is important in those charts
04/18/23 BUS304 – Data Presentation 11
March 2005 New Car Sales
Car Company March 2005 Sales
General Motors 426,114
Ford 305,173
DaimlerChrysler 243,165
Toyota 203,443
Honda 128,548
Nissan 106,042
Chg from Mar 2004
-1.1%
-5.4%
+2.7%
+12.2%
+6.9%
+12.5%
Create a bar chart to represent the sales of Mar 2005 for different brands.Then discuss with another student (group of 2) to create a new graph characterizing the information on the 3rd column. (You can draw the graph,if you are not sure how excel can convey the information.
04/18/23 BUS304 – Data Presentation 12
Pie Chart A way of summarizing a set of categorical data Convenient to present the proportion of each category It is generally more difficult to convey the actual amount
Works especially when there are not too many categories and the proportions are significantly different from categories.
Percentage of People Investing
Mutual Fund22%
Savings Account
31%Certificate of Deposit
9%
Individual Stocks21%
Bonds5%
Real Estate10%
Other2%
Mutual Fund
Savings Account
Certificate of Deposit
Individual Stocks
Bonds
Real Estate
Other
04/18/23 BUS304 – Data Presentation 14
ExerciseUse the data in “Bar Chart” to create a bar
chart. Compare it with the bar chart. Discuss the different information it conveys
04/18/23 BUS304 – Data Presentation 15
Mis-use of a pie chart A pie chart focuses the readers attention on the “proportion”.
Unlike bars, which can be created with multiple series (side-by-side bars), pie chart is focused on one series.
Wrong:
why? 430853.3873
322593.0233
236772.1519
181321.7469
120250.7016
94259.55556
426,114
305,173
243,165
203,443
128,548
106,042General Motors (03/04)
Ford (03/04)
DaimlerChrysler (03/04)
Toyota (03/04)
Honda (03/04)
Nissan (03/04)
General Motors (03/05)
Ford (03/05)
DaimlerChrysler (03/05)
Toyota (03/05)
Honda (03/05)
Nissan (03/05)
04/18/23 BUS304 – Data Presentation 16
Discuss: Student leaders at Boise State University wanted to draw attention to the
funding inequities among the four public universities in Idaho. They collect the following information:
Funding Per Student
Boise State Univ. Univ of Idaho Lewis & Clark College Idaho State Univ.
$5,900 $7,143 $6,320 $5,410
The student leader created
a par chart as shown on the
right to represent the data he
collected. Please comment on
his chart.
04/18/23 BUS304 – Data Presentation 17
Line Chart
Especially useful in statistics and science. To reflect the trend.
Can draw multiple lines in one graph for comparison.
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1996 1997 1998 1999 2000 2001 2002
No. of Men
No. of Women
Note: when using Excel to generate a line chart, the X-axis is stillregarded as categorical names.It does not have numerical value
Note: when using Excel to generate a line chart, the X-axis is stillregarded as categorical names.It does not have numerical value
Exercise: Sheet 4 and 5
Line Chart with Secondary Axis Go to Line Chart 3. The data contains both the Sales and Profit
over the years. Create two line chart, one for sales data, one for profit data. Question: how do we combine these two lines in one chart?
04/18/23 BUS304 – Data Presentation 18
04/18/23 BUS304 – Data Presentation 19
Scatter Chart Mostly used in science and statistics to reflect the
sample location. X-axis and y-axis both have numerical values Shows data correlations (positive, negative, etc.)
04/18/23 BUS304 – Data Presentation 20
Observe data correlation from scatter chart
Find the data from worksheet 6.
Draw scatter chart using
Sq. Feet as x-axis, Price as y-axis
Age as x-axis, Price as y-axis
No. of bedrooms as x-axis, Price as y-axis
No. of bathrooms as x-axis, Price as y-axis
No. of garages as x-axis, Price as y-axis
04/18/23 BUS304 – Data Presentation 21
Summary
4 Basic types of charts:
Bar chart
Pie chart
Line chart
Scatter chart
Know how to create a
chart from Excel
Know how to read the
chart (find a value given
a certain condition)
Know the characteristics,
and be able to pick the
best chart to convey info.
Grouped Data
04/18/23 BUS304 – Data Presentation 23BUS304 – Data Presentation 23
From Raw Data …Raw Survey Data
Raw Survey Data
Surveyee Favorite Cuisine
#1 A
#2 D
#3 E
#4 C
#5 B
#6 E
#7 A
#8 E
#9 C
#10 D
#11 D
… …
What is your favorite type of cuisine?
A) Chinese
B) French
C) Indian
D) Italian
E) Other
04/18/23 BUS304 – Data Presentation 24BUS304 – Data Presentation 24
Frequency Table
Tells us information on the aggregate level
i.e. How many data fall in one specific category
Such information is most statisticians care about
Can be used to transfer to graphs
Frequenc
y
Chinese 10
French 4
Indian 3
Italian 8
Other 4
Total 29
Favorite Cuisine Types
0
2
4
6
8
10
12
Chinese French Indian Italian Other
04/18/23 BUS304 – Data Presentation 25Feb 1, 2006 BUS304 – Data Presentation 25
Relative FrequencyRelative Frequency:
The percentage of times
FrequencyRelative Frequency =
Total Sample of Population Size
Frequency
Chinese 10
French 4
Indian 3
Italian 8
Other 4
Total 29
Relative
Frequency
Chinese 0.344828
French 0.137931
Indian 0.103448
Italian 0.275862
Other 0.137931
Total 1.000000
You can use either a bar chart or a piechart to represent a relative frequency table.
04/18/23 BUS304 – Data Presentation 26
ExerciseCreate frequency and relative frequency tables
for both the male and female surveyees. Compare their different preferences.
04/18/23 BUS304 – Data Presentation 27
For Interval / Ratio Data 16 business executives responded to the question on
how many international trips they made in 2006.
3 0 0 1
1 2 2 0
0 2 1 0
2 1 4 2
Create a frequency and relative frequency to characterize the responses.
04/18/23 BUS304 – Data Presentation 28Feb 1, 2006 BUS304 – Data Presentation 28
When data spread to a wide range
Raw Data
Raw Data
Grouped Data
Grouped Data
Total
0~$10000
$10000~$20000
$20000~$30000
$30000~$40000
… …
Total
Frequency Table
Frequency TableSurveyee Gender Annual Income
#01 F 90213
#02 F 35236
#03 M 45660
#04 M 61508
#05 M 24158
#06 M 57545
#07 F 61559
#08 F 57573
… … …
We divide the data into ranges and count how many fall into the range
We divide the data into ranges and count how many fall into the range
Finish the table and create a bar chart to display the grouped dataHint: you may need to sort the raw data in ascending (or descending) order
Finish the table and create a bar chart to display the grouped dataHint: you may need to sort the raw data in ascending (or descending) order
04/18/23 BUS304 – Data Presentation 29Feb 1, 2006 BUS304 – Data Presentation 29
Histogram
0
3
6
5
4
2
00
1
2
3
4
5
6
7
5 15 25 36 45 55 MoreF
req
uen
cy 0~9 10~19 20~29 30~39 40~49 50~59 More
Histogram
Also called “frequency histogram”
A bar chart converted from the
frequency table:
displays the data distribution:
X-axis shows the data range
Y-axis shows the number of data
fall in to the group
Generally don’t have gap between
bars – why?
Histogram is only for displaying
“continuous interval/ratio data”
Exercise:Adjust the bar chart you havefrom last page to a histogram
Exercise:Adjust the bar chart you havefrom last page to a histogram
04/18/23 BUS304 – Data Presentation 30Feb 1, 2006 BUS304 – Data Presentation 30
Steps to create a histogram
1. Figure out how to group the data
Find the minimal data (rounded down)
Find the maximal data (rounded up)
Find the rough range = max – min
What does the range mean?
Determine how many groups you want to display?
(Not too many, but not too few)
Define the Interval (How wide is each group)
Interval = (range of Data) / (no. of groups)
Generate the ranges and create frequency table
Convert the frequency table to a bar chart (with no gap!)
04/18/23 BUS304 – Data Presentation 31Feb 1, 2006 BUS304 – Data Presentation 31
Extra Notes The actual shape of the histogram depends on the
number of groups Exercise: try to create a histogram using the income data
(data3, sheet2) with 6 groups, 10 groups and 15 groups. Read:
• How many people have an annual income higher than $60000?
• How many are lower than $30000?
Think: • What if I only have 2 groups?
• What if I have 30 groups?
Histogram
0
20
40
60
80
10000~54999 55000~99999 More
Fre
qu
en
cyFinding the right number of
groups to best present the data distributionmay take you several trials.
Finding the right number of groups to best present the data distributionmay take you several trials.