2.5  5Number Summary
2.5  5Number Summary 5Number Summary
 Minimum, \(Q_1\), Median, \(Q_3\), Maximum
 \(Q_1\) is the first quartile, this is the 25th percentile
 \(Q_3\) is the third quartile, this is the 75th percentile
Five number summaries are used to describe some of the key features of a distribution. Using the values in a five number summary we can also compute the range and interquartile range.
 Range

The difference between the maximum and minimum values.
\(Range = Maximum  Minimum\)
Note! The range is heavily influenced by outliers. For this reason, the interquartile range is often preferred because it is resistant to outliers.
 Interquartile range (IQR)

The difference between the first and third quartiles.
\(IQR = Q_3  Q_1\)