8. 8
ข้อแนะนำาข้อแนะนำา
เลือกฟอนต์ที่อ่านง่าย
Eng : Times New Roman หรือ Arial จะอ่าน
ง่ายกว่า Script หรือ Handwriting
ไทย : Cordia New จะอ่านง่ายกว่า
Angsana New
ถ้าต้องการความกว้างตัวหนังสือคงที่
Eng : Courier New
ไทย : Cordia New, Tahoma
19. 19
Tabulating and Graphing Categorical
Data
Univariate data:
Tabulate using a
summary table.
Graph using a bar chart
or a pie chart
Bivariate Data:
Tabulate using a
contingency table.
Graph using a
compound bar chart.
20. 20
Summary Table
1. Lists Categories & Number of Elements
2. Count by Tallying
3. Show Frequencies (Counts) or Percentages
Row Is
Category
Tally:
|||| ||||
|||| ||||
Major Count
Accounting 130
Economics 20
Management 50
Total 200
21. 21
0 50 100 150
Acct.
Econ.
Mgmt.
Bar Chart
Bars for
categorical
variables
Bar Length
Shows
Frequency
Gaps must
exist (1/2 to
1 bar width)
Equal Bar
Widths
Zero Point
Frequency
Major
22. 22
Contingency Table
Level of Study: U U S S U U S S U S
Gender: M F F M M M F M M F
( U=University , S=SecondarySchool ; M=Male , F=Female
)
4 1
2 3
Gender
Level of Study Male Female Total
University 5
SecondarySchool 5
Total 6 4 10
35. 36
Tabulating and Graphing Bivariate
Categorical Data
Investment Investor A Investor B Investor C Total
Category
Stocks 46.5 55 27.5 129
Bonds 32 44 19 95
CD 15.5 20 13.5 49
Savings 16 28 7 51
Total 110 147 67 324
Contingency tables: investment in thousands
of dollars
36. 37
Tabulating and Graphing Bivariate
Categorical Data
Side by side charts
Comparing Investors
0 10 20 30 40 50 60
Stocks
Bonds
CD
Savings
Investor A Investor B Investor C
38. 39
Using “chart junk”
Failing to provide a relative
basis in comparing data
between groups
Compressing the vertical axis
Providing no zero point on the vertical axis
Errors in Presenting Data
40. 41
No Relative Basis
Good Presentation
A’s received by
students.
A’s received by
students.
Bad Presentation
0
100
200
300
FR SO JR SR
Freq.
0
10
20
30
FR SO JR SR
%
FR = Freshmen, SO = Sophomore, JR = Junior, SR = Senior
42. 43
No Zero Point on Vertical Axis
Good Presentation
Monthly Sales
Monthly Sales
Bad Presentation
0
39
42
45
J F M A M J
$
36
39
42
45
J F M A M J
$
Graphing the first six months of sales.
36
56. 57
Compare values between curves or change the
situation of the origin of different data to avoid
comparing in the same conditions.
Bad Presentation
Horizontal bars are used for categorical variables.
Vertical bars are used for numerical variables.
Still, some variation exists on this point in the literature.
Also, there are many variations on the bar (e.g., stacked bar)