What is the term for a population group treated as a statistical unit based on a common characteristic?

The term "cohort" refers to a population group that is treated as a statistical unit because of a shared characteristic or common experience. This term is widely used in research, particularly in fields such as epidemiology and sociology, to analyze specific attributes or trends within a defined group over time. A cohort can encompass various demographics, such as age, gender, or any other defining trait, allowing researchers to draw insights about that particular subgroup.

In contrast, while "sample" refers to a subset of a larger population chosen to represent that population in a study, it does not inherently carry the implication of a shared characteristic. "Demographic" relates to statistical data about populations, often based on categories such as age, race, or income, but is not specifically a statistical unit like a cohort. "Aggregate" describes a collection of data points or features grouped together, but it is more about the collection itself rather than focusing on a specific group with a shared characteristic.