representativitat

Representativitat, or representativeness, denotes the degree to which a person, group, sample, or institution reflects the characteristics of a larger population. In statistics, representativeness concerns how well findings from a sample generalize to the population of interest; bias and sampling error threaten representativeness.

To achieve representativeness, researchers use random sampling, stratified sampling, systematic sampling, and weighting or post-stratification adjustments. The aim is to minimize differences between the sample and the population on key variables such as age, gender, region, or socioeconomic status.

In political science, representativeness refers to how well political bodies reflect or serve their constituents. Two related notions are descriptive representation, the extent that elected officials resemble voters in observable traits, and substantive representation, the extent that officials advocate for and advance voters' preferences. Electoral systems influence representativeness: proportional representation often yields parliaments that mirror vote shares, while plurality systems can distort composition.

Challenges include nonresponse, incomplete information, and demographic or geographic changes over time. Measuring representativeness can be difficult when populations are heterogeneous or hard to define. Concepts of representativity also intersect with ethics and legitimacy, since striving for representativeness can raise questions about who is included or empowered.

Representativeness is a foundational idea in statistics, political theory, and public policy, informing research design, elections, and governance. In practice, complete representativeness is rarely achieved, but recognizing its dimensions helps evaluate methods and outcomes.