Tavoitepopulaation

In Finnish research and policy contexts, tavoitepopulaation, commonly translated as the target population, denotes the entire group to whom a study’s conclusions are intended to apply. It defines the scope of generalizability and guides decisions about sampling, measurement and analysis. The target population is not necessarily the same as the people who participate in the study or are available for recruitment.

A target population differs from related concepts such as the accessible population, the sampling frame, and the study population. The accessible population is the subset that can realistically be reached, given practical constraints. The sampling frame is the actual list or mechanism used to select individuals from the accessible population. The study population comprises the participants who are ultimately included in the analysis.

Defining a target population involves geographic boundaries, time period, demographic or clinical characteristics, and explicit inclusion and exclusion criteria. A precise definition helps ensure clarity and consistency, but there is a trade-off: overly narrow criteria improve homogeneity and internal validity while potentially reducing external validity and generalizability.

An example in health research might illustrate the concept. A study on obesity in Finland could define the target population as all adults aged 18–75 living in Finland during 2024. The accessible population might be adults visiting primary care centers; the sampling frame could be the national health registry; the study sample would consist of those who consent and meet the eligibility criteria.

Implications and methods: To support appropriate generalization, researchers predefine criteria, strive for random sampling when feasible, and transparently report differences between target, accessible, and study populations. When discrepancies exist, weighting and stratified analyses can help, but substantial divergence can limit external validity.