offsetbiasvirheet

Offset bias errors, also called offset biasvirheet in Finnish, are systematic measurement errors defined by a constant deviation between the true value and what a device reports. The offset remains when the input quantity is constant and is not due to random noise. These errors can persist across measurements and calibrations if not properly addressed.

Causes include zero-offset errors in sensors, biases in amplifiers or ADCs, temperature dependence, aging, and improper calibration. Environmental factors, wiring, and signal conditioning can also introduce an offset. Offsets are different from random errors because they produce a consistent baseline shift in the measurements.

Effects of offset bias errors include a consistent bias in all readings, which can distort calibrated results, affect derived parameters, and compromise accuracy. In time series data, an offset appears as a persistent baseline shift that can masquerade as a real signal component if not corrected.

Detection and estimation typically involve calibration with known standards, testing across the operating range, zero checks, and residual analysis. Comparing measurements to a reference instrument helps diagnose and quantify the offset, while regression analysis can estimate the intercept representing the offset value.

Correction and mitigation strategies include software compensation by subtracting the estimated offset, hardware offset trimming, and recalibration. Temperature compensation and improved sensor or electronics design can reduce offset, and regular calibration schedules help maintain long-term accuracy.

Examples of offset bias errors occur in voltage measurement systems with a small constant offset, accelerometers with a bias that shifts baseline readings, and photodiode current measurements with a DC offset. See also bias, systematic error, and DC offset.