What is statistical control and why is it important?
A process is said to be in statistical control when all special causes of variation have been eliminated and only natural (or common) cause variation remains. On a control chart, this is illustrated by data that falls within control limits and by the absence of non-random patterns or trends. Statistical control is important because it shows you what the process is capable of producing over time. Statistical control allows you to make predictions about how the process will run in the future, based on how it ran in the past. It helps you see if the process is currently capable of producing output that meets specifications 100% of the time.
