Survey methodology in the context of "Statistical inference"

In statistics, quality assurance, and survey methodology, sampling is the selection of a subset or a statistical sample (termed sample for short) of individuals from within a statistical population to estimate characteristics of the whole population. The subset is meant to reflect the whole population, and statisticians attempt to collect samples that are representative of the population. Sampling has lower costs and faster data collection compared to recording data from the entire population (in many cases, collecting the whole population is impossible, like getting sizes of all stars in the universe), and thus, it can provide insights in cases where it is infeasible to measure an entire population.

Each observation measures one or more properties (such as weight, location, colour or mass) of independent objects or individuals. In survey sampling, weights can be applied to the data to adjust for the sample design, particularly in stratified sampling. Results from probability theory and statistical theory are employed to guide the practice. In business and medical research, sampling is widely used for gathering information about a population. Acceptance sampling is used to determine if a production lot of material meets the governing specifications.

Health indicators are quantifiable characteristics of a population which researchers use as supporting evidence for describing the health of a population. Typically, researchers will use a survey methodology to gather information about a population sample, use statistics in an attempt to generalize the information collected to the entire population, and then use the statistical analysis to make a statement about the health of the population. Health indicators are often used by governments to guide health care policy or to make goals for improving population health.

Human subjects research is systematic, scientific investigation that can be either interventional (a "trial") or observational (no "test article") and involves human beings as research subjects, commonly known as test subjects. Human subjects research can be either medical (clinical) research or non-medical (e.g., social science) research. Systematic investigation incorporates both the collection and analysis of data in order to answer a specific question. Medical human subjects research often involves analysis of biological specimens, epidemiological and behavioral studies and medical chart review studies. (A specific, and especially heavily regulated, type of medical human subjects research is the "clinical trial", in which drugs, vaccines and medical devices are evaluated.) On the other hand, human subjects research in the social sciences often involves surveys which consist of questions to a particular group of people. Survey methodology includes questionnaires, interviews, and focus groups.

Human subjects research is used in various fields, including research into advanced biology, clinical medicine, nursing, psychology, sociology, political science, and anthropology. As research has become formalized, the academic community has developed formal definitions of "human subjects research", largely in response to abuses of human subjects.