Information Technology Reference
In-Depth Information
Solution
Use
boxplot(
x
)
, where
x
is a vector of numeric values.
Discussion
A box plot provides a quick and easy visual summary of a dataset.
Figure 1-5
shows a
typical box plot:
• The thick line in the middle is the median.
• The box surrounding the median identifies the first and third quartiles; the bottom
of the box is Q1, and the top is Q3.
• The “whiskers” above and below the box show the range of the data, excluding
outliers.
• The circles identify outliers. By default, an outlier is defined as any value that is
farther than 1.5 × IQR away from the box. (IQR is the
interquartile range
, or
Q3 − Q1.) In this example, there are three outliers.
l
l
l
Figure 1-5. Your typical box plot
