Demography

Demography (from Ancient Greek δῆμος (dêmos) 'people, society' and -γραφία (-graphía) 'writing, drawing, description') is the statistical study of human populations: their size, composition (e.g., ethnic group, age), and how they change through the interplay of fertility (births), mortality (deaths), and migration.
Formal demography limits its object of study to the measurement of population processes, while the broader field of social demography (or population studies) also analyses the relationships among economic, social, institutional, cultural, and biological processes that influence a population. Educational institutions usually treat demography as a field of sociology, although independent demography departments do exist.
Demographic analysis (usually abbreviated to DA) examines and measures the dimensions and dynamics of populations, including whole societies or groups defined by criteria such as education, nationality, religion, and ethnicity. The methods of DA have primarily been developed to study human populations, but have also been used in a variety of areas where researchers want to know how other non-human populations of social actors can change across time through processes of birth, death, and migration.
Demographic analysis is used in a wide variety of contexts. In the labor force, DA is used to estimate sizes and flows of populations of workers; in population ecology the focus is on the birth, death, emigration and immigration of individuals in a population of living organisms; in the social sciences this could involve the movement of firms and institutional forms; in business planning DA is often used to describe the population in a business's geographic area.
In the context of human biological populations, demographic analysis uses administrative records to develop an independent estimate of the population. For example, patient demographics such as date of birth, gender, date of death, postal code, ethnicity, blood type, emergency contact information, family doctor, insurance provider data, allergies, major diagnoses, and major medical history form the core of the data for any medical institution, allowing the identification and categorization of a patient for the purpose of statistical analysis.
Demographic analysis estimates are often considered a reliable standard for judging the accuracy of census information. For example, the U.S. Census Bureau expanded its DA categories for the 2010 U.S. Census to include comparative analysis between independent housing estimates, and differences between census address lists at different key times.