studiepopulationen

The study population is the group of individuals from whom data are drawn for a particular research project. It is the subset of the broader target population that meets the study’s eligibility criteria and is available to participate or be observed within the study design and time frame.

A key distinction exists between the target population, the study population, and the sample. The target population is the entire group of interest to the research question. The study population is the portion of that group that actually qualifies and can be recruited under the study’s protocol. The sample consists of the individuals within the study population who are ultimately observed or measured. Clear definitions of inclusion and exclusion criteria help specify who belongs to the study population.

The selection of the study population is typically guided by a sampling frame and chosen through probability or non-probability sampling methods. Inclusion criteria specify characteristics that must be present, while exclusion criteria identify conditions that disqualify potential participants. The goal is to obtain a study population that is representative of the target population to support valid inferences about the broader group.

Representativeness and external validity depend on how the study population is defined and recruited. Biases such as selection bias or nonresponse can limit generalizability. Sample size and attrition affect statistical power and precision. In longitudinal research, the population can be dynamic, with participants entering or leaving the study over time.

Ethical considerations, including informed consent and protection of confidentiality, are essential in defining and recruiting the study population.