Six Sigma Black Belt Certified Practice Exam

In measurement system analysis, which pair of data measures is used to determine total variance?

1. Process variance and reproducibility

2. Noise system and repeatability

3. Measurement variance and process variance

4. System variance and bias

The correct answer is: Measurement variance and process variance

In the context of measurement system analysis, determining total variance involves understanding how different sources of variability contribute to the overall variability in measurements. The correct choice highlights measurement variance and process variance as the two main components used to compute total variance. Measurement variance represents the variability that comes from the measurement system itself, which could include factors like instrument error, operator error, and the environment in which the measurement is taken. It assesses how much the measurement system can vary when measuring the same process under consistent conditions. On the other hand, process variance refers to the natural variability inherent in the process being measured. This encompasses all the variations in the process itself, which can stem from material differences, operational factors, or other external influences affecting the production. When these two variances—measurement and process—are combined, they provide a comprehensive understanding of total variance, which is crucial for identifying areas for improvement and ensuring that the measurement process accurately reflects the process being evaluated. Understanding this relationship is fundamental in Six Sigma methodology as it aids in identifying root causes of variability and forming actions to reduce defects.