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Precision is a description of a level of measurement that yields ''consistent'' results when repeated. It is associated with the concept of "''random error''", a form of observational error that leads to measurable values being inconsistent when repeated. Accuracy has two definitions: * The more common definition is that accuracy is a level of measurement with no inherent limitation (ie. free of ''systematic error'', another form of observational error). * The ISO definition is that accuracy is a level of measurement that yields true (no systematic errors) ''and'' consistent (no random errors) results. ==Common definition== In the fields of science, engineering and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's true value.〔''(JCGM 200:2008 International vocabulary of metrology ) — Basic and general concepts and associated terms (VIM)〕 The precision of a measurement system, related to reproducibility and repeatability, is the degree to which repeated measurements under unchanged conditions show the same results.〔 Although the two words precision and accuracy can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method. A measurement system can be accurate but not precise, precise but not accurate, neither, or both. For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. The result would be a consistent yet inaccurate string of results from the flawed experiment. Eliminating the systematic error improves accuracy but does not change precision. A measurement system is considered ''valid'' if it is both ''accurate'' and ''precise''. Related terms include ''bias'' (non-random or directed effects caused by a factor or factors unrelated to the independent variable) and ''error'' (random variability). The terminology is also applied to indirect measurements—that is, values obtained by a computational procedure from observed data. In addition to accuracy and precision, measurements may also have a measurement resolution, which is the smallest change in the underlying physical quantity that produces a response in the measurement. In numerical analysis, accuracy is also the nearness of a calculation to the true value; while precision is the resolution of the representation, typically defined by the number of decimal or binary digits. Statistical literature prefers to use the terms ''bias'' and ''variability'' instead of ''accuracy'' and ''precision.'' ''Bias'' is the amount of ''inaccuracy'' and ''variability'' is the amount of ''imprecision.'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「accuracy and precision」の詳細全文を読む スポンサード リンク
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