The vital few factors capable of influencing a system under Juran’s Total Quality Control theory are elements of:

In Juran’s Total Quality Control theory, the vital few factors that significantly influence a system are classified as common causes. Common causes are inherent to the process and are usually responsible for the majority of variation in the output of the system. These factors represent systemic issues that can impact quality consistently and predictably over time, thus deserving focused attention for improvement.

Understanding that common causes of variation arise from the process itself is crucial for quality management efforts. By targeting these elements, organizations can implement changes that result in a more stable and effective process. This approach aligns with Juran's philosophy that addressing the vital few—those common causes of quality issues—leads to substantial improvements in overall performance.

In contrast, special causes refer to variations that arise from specific, identifiable events and are typically irregular. While they can affect quality, they do not usually represent the systemic issues addressed through ongoing quality control strategies. Therefore, focusing solely on special causes would lead to improvements that are often temporary and not sustainable in the long term.