Which of the following describes offset as a sensor error?

• A. Offset is a constant difference between the measured value and true value that persists over time.
• B. Offset is a temporary fluctuation around the true value.
• C. Offset is the same as drift.
• D. Offset refers to mechanical wear in the sensor.

Answer: (A)

Offset is a fixed bias in a sensor’s output: the reading is consistently higher or lower than the true value by a constant amount. This means the error remains the same over time for a given sensor and conditions, so you can describe the measured value as true value plus that fixed offset. That steady, additive difference is what defines offset. It’s not just a momentary wobble around the true value (that would be noise or random fluctuation), and it’s not the same as drift, which is a gradual change in the offset itself over time. Mechanical wear can affect many aspects of performance, but offset specifically refers to this constant bias, not a description of wear.