A measure of closeness of agreement between a test result and an accepted reference value.The degree of conformity of an indicated value to an accepted standard value, or ideal value. links Accuracy Rating - A number of quantity defining a limit that errors will not exceed when a device is used under specified operating conditions. Accuracy rating can be expressed in a number of forms, i.e. in terms of the measured variable (± 1°C), percent of span (± 0.5% of span), percent of upper range value (± 0.5% of upper range value F.S.), percent of scale length (± 0.5% of scale length), or percent of actual output reading (± 1% of actual output reading). Measured Accuracy - The maximum positive and negative deviation observed in testing a device under specified conditions and by a specified procedure. It is usually measured as an inaccuracy and expressed as accuracy, typically in terms of the measured variable, percent of span, percent of upper range variable, percent of scale length, or percent of actual output reading. See accuracy, accuracy rating.