## Chapter 15. Statistical Techniques

This chapter covers several topics that relate to basic statistical
techniques. For the most part, these recipes build on those described in
earlier chapters, such as the summary techniques discussed in Chapter 8, and join techniques from Chapter 14. The examples here thus show additional ways to
apply the material from those chapters. Broadly speaking, the topics
discussed in this chapter include:

Techniques for characterizing a dataset, such as calculating
descriptive statistics, generating frequency distributions, counting
missing values, and calculating least-squares regressions or
correlation coefficients

Randomization methods, such as how to generate random numbers
and apply them to randomizing a set of rows or to selecting individual
items randomly from the rows

Techniques for calculating successive-observation differences,
cumulative sums, and running averages.

Methods for producing rank assignments and generating team
standings

Statistics covers such a large and diverse array of topics that this
chapter necessarily only scratches the surface and simply illustrates a
few of the potential areas in which MySQL may be applied to statistical
analysis. Note that some statistical measures can be defined in different
ways (for example, do you calculate standard deviation based on
`n`

degrees of freedom, or
`n`

–1?). If the definition I use for a given term doesn’t match the one you prefer, adapt the queries or algorithms shown here appropriately. ...