Factors affecting accuracy
Accuracy The degree to which the result of a measurement, calculation, or specification conforms to the correct value or a standard. describes the difference between a measurement and the true value. Many factors affect accuracy. This topic discusses the effect percent-of-reading, offset, and resolution have on the accuracy of an analog voltage measurement. Accuracy is defined as follows:
accuracy = percent-of-reading + offset
where percents-of-reading and offsets are displayed in the Analog measurement specifications.
Error discussed in this section and error-related specifications of the data logger do not include error introduced by the sensor, or by the transmission of the sensor signal to the data logger.
Measurement accuracy example
The following example illustrates the effect percent-of-reading and offset have on measurement accuracy. The effect of offset is usually negligible on large signals.
Example:
- Sensor-signal voltage: approximately
- CRBasic measurement instruction:
VoltDiff() - Programmed input-voltage range (
Range) : mV - Input measurement reversal (
RevDiff): True - Data logger circuitry temperature: 10° C
Accuracy of the measurement is calculated as follows:
accuracy = percent-of-reading + offset
where
percent-of-reading =
=±
and
offset =
Therefore,
accuracy = ±(