Which statement about systematic 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 cause random fluctuations.
• D. They are always detected by Cusum charts.

Answer: (B)

Systematic errors cause a constant bias in measurements, which changes accuracy but not the random scatter of results. Because they push all measurements in one direction, the average of many measurements will differ from the true value, revealing the bias when you compare the mean to a known standard. Precision (the spread described by SD or CV) reflects random variability around that biased mean, not the bias itself. So the statement that systematic errors affect accuracy and are confirmed by the mean is the correct one. While tools like Cusum charts can help detect shifts over time, they don’t guarantee detection in every case, and systematic errors are not simply random fluctuations.