Population

The population is the complete set of people, organisations or units your research conclusions are meant to apply to. Defining it precisely — including geography, sector, role and time period — is the first step in any sampling plan.

Distinguish the target population, which is the group you ultimately want to generalise to, from the accessible population, which is the portion you can realistically reach. The sampling frame is the actual list from which you draw, and any mismatch between frame and target population is a source of coverage bias.

Population size feeds directly into sample-size calculation for finite populations, and a vaguely defined population makes the sample impossible to justify. State it in one clear sentence in your methodology chapter, then explain how your sampling frame approximates it and where the gaps lie.