Which of the following are common causes of variation?

Common causes of variation are inherent variations that occur in a process due to a multitude of factors that are usually stable over time. These include human error, equipment variability, and environmental conditions. Human error accounts for mistakes in execution or decision-making during the process. Equipment variability refers to the performance differences that may arise from machinery or tools, which can affect output consistency. Environmental conditions encompass external factors such as temperature, humidity, or other physical surroundings that can impact the process.

These common causes are typically always present in a process and are part of the natural variability that is to be expected over time. Understanding them is crucial for quality control and process improvement efforts, as they help identify where issues lie within a stable process.

In contrast, the other options focus on factors that are more transient or managerial in nature. Management decisions and financial constraints, for example, refer to strategic and budgetary elements that can change frequently and may not reflect the intrinsic characteristics of a process. Similarly, market trends and competitor strategies are external forces that can influence business decisions but do not encapsulate variation within a single process. Lastly, customer feedback and satisfaction surveys are tools for gauging performance perceptions but do not directly relate to the ongoing variability found in processes. Thus, while they are important