Which statement about random errors is true?

• A. They affect precision and are confirmed by SD and CV.
• B. They affect accuracy and are confirmed by mean.
• C. They only occur in calibration steps.
• D. They never affect reproducibility.

Answer: (A)

Random errors cause data to scatter around the true value, so they reduce precision. Precision is about how tightly repeated measurements cluster, and this clustering is what SD and CV quantify—the smaller the dispersion, the higher the precision. The mean of many measurements can still be close to the true value because random errors tend to cancel out on average, which is why accuracy is tied more to systematic bias than to random scatter. Systematic errors shift the average away from the true value.

Random errors can occur at any stage of measurement, not just during calibration, and they do affect reproducibility since they introduce variability between repeated measurements or runs.