<P> Instrument error refers to the combined accuracy and precision of a measuring instrument, or the difference between the actual value and the value indicated by the instrument (error). Measuring instruments are usually calibrated on some regular frequency against a standard . The most rigorous standard is one maintained by a standards organization such as NIST in the United States, or the ISO in European countries . However, in physics--precision, accuracy, and error are computed based upon the instrument and the measurement data . Precision is to 1 / 2 of the granularity of the instrument's measurement capability . Precision is limited to the number of significant digits of measuring capability of the coarsest instrument or constant in a sequence of measurements and computations . Error is ± the granularity of the instrument's measurement capability . Error magnitudes are also added together when making multiple measurements for calculating a certain quantity . When making a calculation from a measurement to a specific number of significant digits, rounding (if needed) must be done properly . Accuracy might be determined by making multiple measurements of the same thing with the same instrument, and then calculating the result with a certain type of math function, or it might mean for example, a five pound weight could be measured on a scale and then the difference between five pounds and the measured weight could be the accuracy . The second definition makes accuracy related to calibration, while the first definition does not . </P> <P> The instrument error is not like random error, that can't be removed . Sometimes the removal of instrument errors are very easy, but it is case dependent . In Engineering instruments, like voltmeter or ammeter for example, the instrument error is very difficult to remove . Ammeter has built in resistance, which can't be removed either way . So the only way is to minimize it . On the other hand, the removal of error of a thermometer is a bit simple . Only the calibration has to be removed and then again calibrate it carefully . Sometimes, the user doesn't care for removal of error from the instrument, else he compensates it in calculation, for example, the zero error in Vernier Caliper is eliminated by proper calculation . </P> <P> Another way to deal with instrument error may be to reduce the reactivity of the system to being measured by using some sort of Weak measurement . That is, taking far more, but far less powerful readings to avoid changing the system by the act of measuring . </P>

What kind of instrument will minimize random error