1 CLASS LECTURE NOTES - What is Applied Statistics ...

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BOX PLOT
This is due to J. Tukey and provides
Box Plot of City MPG vs Size
a great deal of information about the
45
data. This plot describes the data by
a rectangle whose lower and upper
35
limits are the first and third quartiles,
respectively. The median (50th
25
percentile or second quartile) is
designated by a horizontal line
15
Small Midsize Compact Large Sports Van
segment inside the rectangle box.
size
The average value is marked by a
symbol such as "x" or "+". The width of the box is usually arbitrary. The main steps for a box plot
are: (a) Calculate the mean and the quartiles of the data; (b) Calculate the inter-quartile range(IQR);
(c) Draw a box with a convenient width such that the upper edge is at the third quartile, lower edge
is the first quartile, a horizontal line within the box identifying the median, and put an "x" to identify
the mean; (d) Draw vertical lines from the center of the upper and lower edges of the box to the most
extreme data values (that are no farther than 3 IQR); (e) Plot all points that are more extreme than
the vertical lines.
mpg_c
PARETO CHART
Pareto Chart for : Failures
Solder Defects (Messina:SQC for MM, 1987)
Percent
100
80
60
40
20
800
700
600
500
400
300
200
100
Number of Occurrences
0
Defect
Insufficient so
Blow holes
Unwetted
Unsoldered
Pinholes
Shorts
0
Count
Percent
Cum %
440
55.0
55.0
120
15.0
70.0
80
10.0
80.0
64
8.0
88.0
56
7.0
95.0
40
5.0
100.0