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Shapes of Distributions. Frequency Distributions. Ex:. Frequency Polygon. Frequency Polygon. The greater the number of participants, the smoother the polygon shape - Curve. Normal Curve. Normal Curve Aka…Bell Curve, Bell-Shaped Curve, The Curve Shape found often in nature - PowerPoint PPT Presentation
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Shapes of Distributions
Frequency Distributions• Ex: X F
15 1
16 0
17 2
18 5
19 8
20 4
21 3
22 1
N= 24
Frequency Polygon
Frequency Polygon
• The greater the number of participants, the smoother the polygon shape- Curve
Normal CurveNormal Curve
Aka…Bell Curve, Bell-Shaped Curve, The CurveShape found often in natureUsed as the basis for a number of inferential statistics
Normal Distribution Examples
The Measures of Central Tendency and Distribution
When the mean, median, and mode are all at the same point, the center of the distribution, the data is considered to be normally distributed.
Mean, Median, Mode
The Measures of Central Tendency and Distribution
When data is skewed, values have “bunched” up at one end or the other.
With skewed data, the mean, median, and mode are usually all different values.
The distribution of the data can be positively or negatively skewed.
Positive Skew
Negative Skew
Bimodal
Distribution Shapes
Distribution Shapes
p. 19 Chapter 3 # 10
• Frequency Distribution and Percentages• Frequency Polygon based on Percentages• Number of Days Absent from Schools for a
sample of 10th graders• n = 28
Class Interval f %
6 – 13
13 – 20
20 – 27
27 – 34
34 – 41
41 – 48
48 – 55
55 – 62
62 – 69
69 – 76
76 – 83
83 – 90
90 – 97
97 – 104
104 – 111
111 - 118
Class Interval f %
6 – 13 2
13 – 20 3
20 – 27 8
27 – 34 4
34 – 41 3
41 – 48 1
48 – 55 2
55 – 62 1
62 – 69 1
69 – 76 0
76 – 83 1
83 – 90 0
90 – 97 1
97 – 104 0
104 – 111 0
111 - 118 1
Class Interval f %
6 – 13 2 7.1
13 – 20 3 10.7
20 – 27 8 28.6
27 – 34 4 14.3
34 – 41 3 10.7
41 – 48 1 3.6
48 – 55 2 7.1
55 – 62 1 3.6
62 – 69 1 3.6
69 – 76 0 0.0
76 – 83 1 3.6
83 – 90 0 0.0
90 – 97 1 3.6
97 – 104 0 0.0
104 – 111 0 0.0
111 - 118 1 3.6
0-613-20
27-3441-48
55-6269-76
83-90
97-104
111-1180
5
10
15
20
25
30
35
Attendance: Percentages
Attendance
Frequency Polygon w/ Percentages
0-6
118-
120
0-613-20
27-3441-48
55-6269-76
83-90
97-104
111-1180
1
2
3
4
5
6
7
8
9
Attendance: Frequencies
Attendance
0-6
118-
120
