The use of terms in enzyme immunoassays

Accuracy, precision, and sensitivity are very loosely used terms, generating considerable confusion. Obviously, results of EIA cannot be meaningfully interpreted nor can theoretical considerations be made if such important basic concepts are not clearly distinguished. Unfortunately, this confusion persists even in advanced theoretical treatments or in data processing. 

A great deal of confusion also surrounds the terms accuracy and precision (Fig. 1.1). Accuracy is the conformity of a result to an 

In order to achieve satisfactory accuracy, it is essential to avoid errors. However, distinction should be made between experimental errors and mistakes. Mistakes are the type of errors ( blunders ) which necessitate the repetition of the test, whereas experimental errors are inherent to the test and may result from random error, from bias or from both. Random errors may be due to slight fluctuations in measuring enzyme activity, variations in temperature, ionic composition of the sample, etc., and can be minimized by the use of standards. Bias is a systematic error (storage effects, improper 

Specificity, another frequently misused term in EIA, should refer to the degree of discrimination of the assay between negative and positive samples (i.e., relative affinities of two systems). 

Many names and acronyms are in use to identify the various assays. This is avoided here, mainly to eliminate the ambiguities when similar acronyms are used for different tests, e.g. CELISA for cellular enzyme-linked immunosorbent assay (Morris et al., 1982), for chemiluminescent enzyme-linked immunosorbent assay (Prono-vost et al., 1981), and for complement enzyme-linked immunosorbent assay (Tandon et al., 1979). 

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