What is the main purpose of a P-Chart in quality control?

The main purpose of a P-Chart, or Proportion Chart, in quality control is to monitor the proportion of defectives in a process over time. This type of chart is particularly useful when dealing with attributes that are binary in nature, such as whether a product is defective or not. By plotting the percentage of defective items against time, quality analysts can visually assess the process stability and identify trends, shifts, or any potential issues that may require intervention.

P-Charts are essential tools for understanding process capability concerning quality standards since they provide a clear picture of the performance of a process in terms of its defect rates. This makes them a critical element in continuous improvement efforts and helps organizations maintain product and service quality.

In contrast, other options focus on different monitoring aspects that are not applicable to the P-Chart. Cumulative defect tracking and evaluating operational specifications typically fall under different chart types or methodologies, while measuring the linearity of instruments is a technical consideration in calibration rather than a quality monitoring technique.