stratify

Stratify is a verb meaning to form or arrange something into distinct layers or strata, or to divide a population or material into such layers. The noun stratification refers to the resulting arrangement and the process that produces it. The term derives from the Latin stratum, layer.

In geology and earth science, stratification describes the layering of sedimentary rocks or soils, and the study of these layers is stratigraphy. Layers form through processes such as deposition, erosion, and diagenesis, and they document changes in the environment, climate, or biological activity over time. Stratified rocks are typically described by horizons or beds with varying composition, grain size, and mineral content.

In sociology and anthropology, social stratification refers to the ranking of individuals or groups in a hierarchical order based on socioeconomic criteria such as income, education, occupation, and prestige. This structural layering affects access to resources and life opportunities and is a central concept in theories of inequality and social mobility.

In statistics and research methods, stratification refers to dividing a population into homogeneous subgroups, or strata, before sampling. Stratified sampling draws samples from each stratum to improve precision and representativeness. The strata can be defined by known characteristics, and samples may be proportional or disproportionate, with weights used to combine results.

Risk stratification is used in medicine and public health to categorize individuals by predicted risk of adverse outcomes, guiding screening and treatment decisions. In ecology and environmental studies, stratification can describe layered habitats or canopy structure.