Sampling and Estimation

In statistics, we rarely have access to an entire population. Instead, we collect a sample and use it to estimate population parameters. This lesson covers sampling methods, the concept of a sampling distribution, and how to construct confidence intervals.

---

Why Sampling?

Studying an entire population is often impractical or impossible:

Reason	Example
Cost	Surveying every household in a country
Time	Testing every item from a production line
Destructive testing	Crash-testing every car produced
Infinite population	All possible measurements of a physical constant

A well-chosen sample can provide reliable estimates of population parameters.

---

Sampling Methods

Probability Sampling (Random)

Every member of the population has a known, non-zero chance of being selected.