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In statistics, a proxy or proxy variable is a variable that is not in itself directly relevant, but that serves in place of an unobservable or immeasurable variable. [1] In order for a variable to be a good proxy, it must have a close correlation, not necessarily linear, with the variable of interest. This correlation might be either positive ...
Examples of proxies include stable isotope measurements from ice cores, growth rates in tree rings, species composition of sub-fossil pollen in lake sediment or foraminifera in ocean sediments, temperature profiles of boreholes, and stable isotopes and mineralogy of corals and carbonate speleothems. In each case, the proxy indicator has been ...
Most paleothermometers are based on empirically-calibrated proxy relationships, such as the tree ring or TEX 86 methods. Isotope methods, such as the δ 18 O method or the clumped-isotope method, are able to provide, at least in theory, direct measurements of temperature.
Tree-ring width, for example, is considered a reliable proxy of ambient environmental conditions such as the warmth of growing seasons or amount of rainfall. Although scientists cannot directly measure the temperature of past years, tree-ring width and other climate proxies have been used to provide a semi-quantitative record of average ...
The blue line represents global surface temperature reconstructed over the last 2,000 years using proxy data from tree rings, corals, and ice cores. [1] The red line shows direct surface temperature measurements since 1880. [2] Global surface temperature (GST) is the average temperature of Earth's surface.
The proloculus (the first chamber) sizes of benthic forams are affected by sea water temperature and their mean has been used as proxy for paleoclimatic investigations. [ 2 ] Mean test diameters of the planktonic foraminifer Orbulina universa have been used to interpret sea surface temperature history in Somali Basin.
Routine health outcomes measurement is the process of examining whether or not interventions are associated with change (for better or worse) in the patient's health status. This change can be directly measured (e.g. by rating scales used by the clinician or patient) or assumed by the use of proxy measurement (e.g. a blood test result).
The English language has a number of words that denote specific or approximate quantities that are themselves not numbers. [1] Along with numerals, and special-purpose words like some, any, much, more, every, and all, they are quantifiers. Quantifiers are a kind of determiner and occur in many constructions with other determiners, like articles ...