Which one of the following best describes how the capability of a process using discrete data should be expressed?

The description of a process's capability using discrete data is best expressed through metrics such as percent defective, defects per unit, or a DPMO (Defects Per Million Opportunities) level. Discrete data usually pertains to countable outcomes, often relating to pass/fail, yes/no, or similar categorical classifications. In this context, it is essential to focus on performance measures that reflect how many units are defective or how often defects occur, allowing for a clearer understanding of the process's quality.

Using percent defective allows for easy interpretation of quality levels by indicating the proportion of defective items in a sample. Defects per unit offers insight into how many defects are typically observed per unit of measure, facilitating a straightforward analysis of the overall process performance. DPMO provides a standard measure that can be used to compare different processes or products, showing how many defects occur per million opportunities, which makes it particularly useful in quality control and continuous improvement efforts.

The other options, while relevant to process capability in certain contexts, do not suit the expression of capability for discrete data as effectively. For example, Cp and Cpk values (which are measures of capability) are primarily applicable to continuous data. Similarly, the terms mu and sigma reference the mean and standard deviation,