Many physical properties influence the performance of a sensor. Temperature, Power supply variance, external electromagnetic influence and time will all have an effect on a sensor. If all these factors are held constant, than the unit will be exactly repeatable. Temperature effects are listed in the specifications of each part. Effects from power supply variation will be attenuated at least 80 dB for example. Hall effects used in some of the ratios will drift over time.
For measurements taken over short periods of time at a fixed external environment, a variance of less than .1% can be expected, and its probably much better than that.
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