Which of the following equations is used to calculate process capability for attribute data?

The correct answer is A. DPMO = DPO × 1,000,000 . In CSSBB, attribute data are discrete counted data such as defects, defectives, pass/fail outcomes, or error counts. For this type of data, process performance is commonly expressed using defects per unit (DPU) , defects per opportunity (DPO) , and defects per million opportunities (DPMO) rather than variable-data capability indices like Cp or Pp . The CSSBB materials distinguish capability indices such as Cp and Pp as formulas for continuous variable data with specification limits, while attribute performance uses defect-based metrics.

Among the listed equations, only DPMO = DPO × 1,000,000 applies to attribute data capability/performance measurement. Option B and option C are variable-data capability formulas based on the spread of a measured continuous characteristic relative to specification limits. Option D is the correlation coefficient formula and is unrelated to capability. Therefore, when the question asks for the equation used to calculate process capability for attribute data , the best CSSBB-aligned answer is A .