Transcript Statistic Descriptive

Chapter 2.
Describing Data
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Chapter 2.
Describing Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
1
Constructing A Frequency Table
 Frequency table:
a grouping of qualitative data into mutually
exclusive classes showing the number of
observation in each class.
Class frequency:
the number observations in each class
Table 2-1 Page 22
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
2
Table 2-1 Frequency Table For Vehicles
Sold At Whitner Autoplex Last Month
Car Type
Number Of Car
Domestic
50
Foreign
30
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Constructing A Frequency Table
(continued)
 Relative class frequencies:
show the fraction of the total number
of observation in each class.
Table 2-2 Page 23
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Table 2-2 Relative Frequency Table
Of Vehicles Sold
Vehicle Type
Number Sold
Relative
Frequency
Domestic
50
50/80 =0.625
Foreign
30
30/80=0.375
Total
80
80/80=1
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Constructing A Frequency Table
(continued)
 Graphic presentation of qualitative data:
- bar chart
a graph in which the classes are
reported on the horizontal axis,
and the class frequencies on the
vertical axis.
Chart 2-1 Page 23
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Constructing A Frequency Table
(continued)
 Graphic presentation of qualitative data:
- Pie chart
a chart that shows the proportion or
percent that each class represents of the
total number of frequencies.
Chart 2-2 Page 24
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Constructing Frequency
Distributions: Quantitative Data
 Frequency distribution:
a grouping of data into mutually
exclusive classes showing the number
of observations in each class.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Table 2-4 Page 28
Prices of vehicles sold last month at
Whitner Autoplex
$23197 $23372 $20454
$26651
………………………………………………………………
……………………………………………………………..
n = 80
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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The Steps For Organizing Data Into
A Frequency Distribution
 Step 1: Decide on the number of
classes.
 Step 2: Determine the class interval
or width.
 Step 3: Set the individual class limits.
 Step 4: Tally the vehicle selling prices
into the classes.
 Step 5: Count the number of items in each
class.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Step 1: Decide on the number of
classes
n = 80
If k = 6 (k is number of classes)
Then: 2k
26 = 64, still less than 80
not using k =6
If k = 7
Then: 2k
27 = 128, greater than 80
Decide at least k = 7
Can choose k more than 7
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Step 2: Determine the class
interval or width
i more or equal (H – L)/ k
i = class interval
H = the highest observed value
L = the lowest observed value
H = 35925
L = 15546
i = (35925-15546)/7 = 2911 = 3000
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Step 3: Set the individual class
limits
15000
18000
21000
24000
27000
30000
33000
up
up
up
up
up
up
up
Chapter 2. Describing
Data
to
to
to
to
to
to
to
18000
21000
24000
27000
30000
33000
36000
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Step 4: Tally the vehicle selling
prices into the classes
Class
15000
18000
21000
24000
27000
30000
33000
up
up
up
up
up
up
up
to
to
to
to
to
to
to
Chapter 2. Describing
Data
18000
21000
24000
27000
30000
33000
36000
Tallies
IIIII III
IIIII IIIII IIIII IIIII III
IIIII IIIII IIIII II
IIIII IIIII IIIII III
IIIII III
IIII
II
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Step 5: Count the number of items
in each class
Selling Price
15000 up to
18000 up to
21000 up to
24000 up to
27000 up to
30000 up to
33000 up to
TOTAL
Chapter 2. Describing
Data
18000
21000
24000
27000
30000
33000
36000
Frequency
8
23
17
18
8
4
2
80
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Class Intervals And Class Midpoints
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Relative Frequency Distribution
 A relative frequency distribution:
converts the frequency to a percent.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Selling Price
15000 up to
18000 up to
21000 up to
24000 up to
27000 up to
30000 up to
33000 up to
TOTAL
Chapter 2. Describing
Data
18000
21000
24000
27000
30000
33000
36000
Frequency
8
23
17
18
8
4
2
80
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
Relative Freq
0.1
0.2875
0.2125
0.2250
0.1
0.05
0.025
1.00
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Graphic Presentation Of A
Frequency Distribution:
1. Histogram.
2. Frequency polygon.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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 Histogram:
a graph in which the classes are
marked on the horizontal axis and the
class frequencies on the vertical axis.
The class frequencies are represented
by the heights of the bars and the
bars are drawn adjacent to each
other.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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 Frequency polygon:
the class midpoints are connected
with a line segment.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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Chapter 2. Describing
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Quiz
The following is the number of minutes
to commute from home to work for a
group of automobile executives;
28 25 48 37 41 19 32 26 16 23 23 29
36 31 26 21 32 25 31 43 35 42 38 33
28
Make frequency distribution included
relative freq.
Chapter 2. Describing
Data
Ir.Muhril Ardiansyah,M.Sc.,Ph.D.
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