โ Scribed by Peter M Chapman
No coin nor oath required. For personal study only.
The word ''index'' comes from Latin and means a pointer, sign, indicator, list, or register. It is used in economics, anthropology, physics, mathematics, astronomy, and a number of other disciplines. An index as used in science can be defined as a number, derived from a formula, that summarizes some quantity of data. For instance, a diversity index can be defined as a statistic that is intended to measure the differences among different biological communities. Indices are most commonly used for the purposes of making comparisons between 2 or more data sets over time. An index is, in the simplest terms, a ratio that measures change and allows us to compare the magnitude of different kinds of changes.
Indices are attractive in science and especially for the communication of science to nontechnical audiences. Indices summarize complex data sets, usually into a single number that is easy to understand, particularly for judges in a court of law and members of the public.
Alas, indices rarely reflect reality. For both regulated and regulating communities, indices are misleading at best and attractive delusions at worst. Indices should not be used as ''bright lines'' for establishing regulatory requirements such as discharge permits or environmental remediation objectives. At the very least, indices should not be used without detailed explanation to convey the important aspects of variability inherent in all environmental conditions. For instance, Washington (1984) provides an excellent review of diversity, biotic, and similarity indices, showing how biological indices are often misused because they are: 1) typically highly specialized to compare and contrast conditions associated with a particular type of water pollution, usually organic pollution; 2) limited to specific geographic areas; and 3) of limited ecological relevance because they do not clearly separate natural environmental change from change related to various types of anthropogenic stressors. Used outside their appropriate context, environmental indices may not accurately describe the single or multiple environmental conditions they are intended to communicate. They are, rather, merely attractive delusions.
Unfortunately, Washington's (1984) review of biological indices and the use of indices in general was published well before the advent of Internet search engines and thus is generally forgotten by the scientific community. Green and Chapman (2011) resurrected the Washington article, together with even earlier and more recent publications in a review of the proper use of environmental indices, and concluded that credible scientists should not be developing or relying on single-number representations of complex data, and they should not be misleading nonscientists that this is appropriate or even useful.
The reduction of complex information to an index by necessity results in the loss of information, which can and does result in misleading interpretations of the original, much more complex, data set. Using more than 1 index usually is not helpful, because they are often highly correlated,
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Deadly Delusions (A Dr. Annabel Tilson Novel Book Two) There are forces at work in Victor Blakes mind. Under the auspices of a stellar attending doctor, medical student Annabel Tilson flourishes on her psychiatry rotation where Victor Blake is the first patient safely ensconced in her car