15.5 Tools for describing sampling variation

As we have observed previously, making decisions about population parameters based on a sample statistic can be difficult: Every sample is likely to be different, and can produce a different value of the sample statistic.

In this chapter, though, a process for making decisions has been studied (Fig. 15.1). To apply this process to research, we need to describe how sample statistics vary from sample to sample (sampling variation). To do so, some of those tools are discussed in the following chapters:

• Tools to describe the population and the sample: Chap. 17.
• Tools to describe how sample statistics vary from sample to sample (sampling variation), and hence what to expect from the sample statistic: Chap. 18.
• Tools to describe the random nature of what happens with sample statistics, and so determine if the sample statistic is consistent with the assumption: Chap. 16.