In quality control, what does a high coefficient of variance indicate?

A high coefficient of variance (CV) is indicative of inconsistent results and low precision in a set of data. The coefficient of variance is calculated as the ratio of the standard deviation to the mean, expressed as a percentage. When this value is high, it demonstrates that the spread of the results is large relative to the average of those results, which means there is a significant degree of variability.

In quality control, a high CV suggests that repeated measurements or tests yield widely varying outcomes, which is undesirable in laboratory settings that prioritize accuracy and reliability. This inconsistency can arise from numerous factors, such as insufficient calibration of instruments, variations in sample handling, or differences in technician performance.

The other choices, while related to the concepts of precision and variability, do not accurately describe the implications of a high coefficient of variance. High precision would correlate with a low CV since consistent results yield a smaller standard deviation relative to the mean. Similarly, low variability in test results would also reflect a low CV, indicating reliability. Excessive control samples could lead to a range of different issues but would not inherently affect the coefficient of variance in the way that variability does.