Population/Sample

Defining the Population

An important step that researchers take in designing their studies is to identify the population of objects or events that they want to understand. The universe of these objects or events is often called the target population. Target populations exist on many levels. They may include individuals, social roles (e.g., parents), positions (e.g., city health department directors), and relationships (marital partners). Target populations may also include social groupings, such as families, organizations, classrooms, cities. In addition, researchers often study nonhuman entities, such as news content, blog posts, videos, texts, and physical spaces. As part of their studies, researchers need to clearly define what units constitute the population. For example, when studying online comments, researchers need to determine whether individual posts make up the population or whether complete threads are the appropriate unit of analysis.

Once researchers have identified their units of analysis, they need to carefully define their population of interest, including key characteristics that should or should not be included in the population. For example, in a study of marital partners,[Page 1284] a researcher might want to specify that the marital partners must be living in the same residence and have been married for a certain length of time. The researcher might also want to specify whether the population includes marital partners of the same or opposite sexes and/or whether the partners have or do not have children. Once researchers have considered important characteristics for inclusion and exclusion in the clearly defined population, they also need to identify known characteristics that exist in the population that are important to be represented in the population.

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