Science and engineering in Manchester chemist visited Manchester in the 1840s. In his research in Manchester, Smith discovered the existence of acid rain, a by product of the industrial revolution. Smith consequently pushed for greater environmental awareness and helped to found the Noxious Vapours Abatement Society in Manchester, which raised awareness of the consequences of poor air. Joseph Whitworth was an engineer and inventor who hailed from Stockport, Cheshire (now Greater Manchester). A talented mechanic amongst various other engineering roles, for long periods of his life, he worked in factories in Manchester. Whitworth would ultimately devise a standard screw thread system, the first of its
Accuracy and precision "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