In general, it is often useful to make decisions using quantitative data but making those decisions can be somewhat arbitrary without a mathematical basis supporting those decisions. In this chapter, you will consider a number of ways to use point values to represent a given set of data. Each of these quantitative metrics will be called a "statistical measure" and will, in some fashion, describe using one number some property of the entire data set. Such measures are part of what is known as "descriptive statistics". Later, you will learn about how other metrics can be used to predict properties of the underlying situation. Doing this is part of what is known as "inferential statistics".