Shape of distribution
(b)Determine the type of
skewness of the distribution
Skewness of distributions
What is the skewness of the
following distributions?
Income
Easy test
Hard test
10
Coefficient of Skewness
11
Interpreting Coefficient of Skewness
Values range from -3 to +3
Box plot
Also known as box-and-whisker plot.
13
Example
Draw a box-plot for the following
data:
15, 13, 6, 5, 12, 28, 22, 18
Skewness from box plot
15
Outliers
•An extremely high or an extremely
low data value when compared with
the rest of the data values.
•Discuss examples
When is a value an
outlier?
When the value is
a) greater than Q3 + 1.5(interquartile range)
b) less than Q1 – 1
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