In this chapter, we will be introduced to the fundamental concept of sampling. We'll also learn about resampling and why it's important.

Sampling is the process of selecting a subset of observations from the population with the purpose of estimating some parameters about the whole population. Resampling methods, on the other hand, are used to improve the estimates of the population parameters.

In this chapter, we will cover the following recipes:

• Introduction to sampling
• k-fold and leave-one-out cross-validation
• Bootstrap sampling