Control chart fundamentals (X̄-R charts, p-charts), process capability indices (Cp, Cpk), common cause vs. special cause variation, and the Western Electric out-of-control signal rules.
Statistical Process Control monitors a process while it runs, using data collected in real time to distinguish a process's routine, common cause variation from a special cause signaling something has actually changed — in time to act before an out-of-spec part is produced, not only after. This module builds X̄-R charts for continuous data and p-charts for attribute data, the Western Electric rules for reading pattern-based out-of-control signals a single point beyond the limit would miss, and the Cp/Cpk capability indices that answer a different question entirely: given a stable process, can it actually meet its specification?
By the end of this module you should be able to explain why a process can be perfectly in control and still incapable of meeting its specification, and why a strong Cp paired with a weak Cpk points to a specific, cheap fix — centering the process — rather than a harder one.