Proxy (statistics) in the context of "Indicator organism"

In business, engineering, and manufacturing, quality – or high quality – has a pragmatic interpretation as the non-inferiority or superiority of something (goods or services); it is also defined as being suitable for the intended purpose (fitness for purpose) while satisfying customer expectations. Quality is a perceptual, conditional, and somewhat subjective attribute and may be understood differently by different people. Consumers may focus on the specification quality of a product/service, or how it compares to competitors in the marketplace. Producers might measure the conformance quality, or degree to which the product/service was produced correctly. Support personnel may measure quality in the degree that a product is reliable, maintainable, or sustainable. In such ways, the subjectivity of quality is rendered objective via operational definitions and measured with metrics such as proxy measures.

In a general manner, quality in business consists of "producing a good or service that conforms [to the specification of the client] the first time, in the right quantity, and at the right time". The product or service should not be lower or higher than the specification (under or overquality). Overquality leads to unnecessary additional production costs.

Marine primary production is the chemical synthesis in the ocean of organic compounds from atmospheric or dissolved carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. Almost all life on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are called primary producers or autotrophs.

Most marine primary production is generated by a diverse collection of marine microorganisms called algae and cyanobacteria. Together these form the principal primary producers at the base of the ocean food chain and produce half of the world's oxygen. Marine primary producers underpin almost all marine animal life by generating nearly all of the oxygen and food marine animals need to exist. Some marine primary producers are also ecosystem engineers which change the environment and provide habitats for other marine life.

Bone density, or bone mineral density (BMD), is the amount of bone mineral in bone tissue, measured as mass of mineral per volume of bone (relating to density). Clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of a hospital or clinic. The measurement is painless and non-invasive with low radiation exposure. Measurements are usually made over the lumbar spine and the upper part of the hip. The forearm may be scanned if the hip and lumbar spine are not accessible.

There is a statistical association between poor bone density and a higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to substantial medical costs, inability to live independently, and even risk of death. Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength.