Analog Instrumentation and Measurement:

Measurements may be direct (direct measurement implies a measuring device displays or provides the magnitude of the value being measured) or indirect (indirect measurements are usually obtained by calculation or some kind of processing the information). One author ^[1] breaks instrumentation into either using "dumb instruments" (where the instrument measures the variable and it is up to the observer to process the data), or "intelligent instruments" (where, after the measurement of the variable is made, further processing and refining the data is made and presented to an observer or to a computer). These intelligent instruments are more likely to be in the digital area (most digital instrumentation is interfaced with analog transducers).

The specific quantity to be measured is referred to as the measurand. To have faith in the results of the measurement of the measurand, one should be concerned with both the accuracy and the precision (they are different, one may have high precision and low accuracy) and the