23.1 Population and Sample

This is a refresher on terminology regarding sampling.

• Population ($N$): The complete set of all elements under study.
• Sample ($n$): A subset of the population selected for analysis.
• Parameter: A numerical measure that describes a characteristic of a population (e.g., population mean $\mu$, population variance $\sigma^2$).
• Statistic: A numerical measure computed from a sample, used to estimate a population parameter (e.g., sample mean $\bar{x}$, sample variance $s^2$).

A well-chosen sample ensures that results generalize to the population, reducing sampling bias.

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