Six Sigma Green Belt Certification Practice Exam

Process capability is calculated as the average number of nonconformities in a sample of fixed size when using which type of charts?

1. u chart

2. c charts

3. p chart

4. np chart

The correct answer is: c charts

Process capability is a critical aspect of quality control that measures how well a given process can produce output within specified limits. In the context of attributes control charts, the calculation of process capability focuses on the average number of nonconformities in a sample. The correct response is based on the nature of the c chart. The c chart is specifically designed to monitor the count of nonconformities per unit within a sample of fixed size (constant). It is utilized when you want to assess the number of defects (nonconformities) in a specific area or over a series of units where that area or these units remain constant. The average number of nonconformities (c) is calculated, allowing for the evaluation of process capability with respect to the number of defects that occur. In contrast, other chart types serve different purposes. For example, the u chart monitors the average number of nonconformities per unit - which can vary if the sample size changes; the p chart is used to monitor the proportion of defective units in a sample, rather than the count of defects; and the np chart deals with the actual number of defective items in a sample but does not directly focus on the nonconformities per unit in the same way the