What type of error occurs when measurements consistently differ due to calibration or reading mistakes?

The correct answer is systematic error, which refers to consistent inaccuracies that occur in measurements due to problems like calibration issues or reading errors. When a measurement consistently deviates in the same direction from the true value, it indicates a systematic error rather than random fluctuations. This type of error can often be identified and corrected through calibration of instruments or careful review of reading techniques.

In the context of experimental work, recognizing systematic errors is crucial as they impact the reliability of the results. For example, if a scale is not calibrated correctly, it will yield measurements that are consistently off, leading to inaccurate data interpretation.

Random uncertainty, on the other hand, is characterized by uncontrolled variations that arise from unpredictable fluctuations in measurement, making them less consistent and more variable. Measurement error is a broader term that can encompass both systematic and random errors, but does not specify the nature of the deviation. Instrumental error focuses specifically on errors originating from the measuring device itself, but systematic errors can arise from various sources, not limited to the instrument. Thus, systematic error is the most precise designation for consistent discrepancies arising from calibration or reading mistakes.