13.8 Summary

Quantitative data can be summarised numerically, and the most common techniques are indicated in Table 13.9. The mean and standard deviation are usually used whenever possible, for practical and mathematical reasons. Sometimes quoting both the mean and median (and the standard deviation and IQR) may be appropriate.

The following short video may help explain some of these concepts:

TABLE 13.9: Summarising quantitative data
	For distributions that are:
Feature:	Approximately symmetric	Not symmetric, or outliers
Average:	Mean	Median
Variation:	Standard deviation	IQR
Shape:	Verbal description only	Verbal description only
Outliers:	Standard deviation rule	IQR rule