Chapter 5: Control Charts for Attributes
Abstract: Control charts for attributes in Statistical Process Control (SPC) monitor quality when data is counted (pass/fail, yes/no) rather than measured, using charts like P (proportion defective) , np (number defective) , C (number of nonconformities) , and U (average number of nonconformities) to distinguish common (natural) variation from special (assignable) cause variation, helping maintain process stability . These charts plot data over time, showing if a process is stable (in control) or has unusual patterns (out of control). Types of Attribute Control Charts P-Chart (Proportion Nonconforming): Tracks the fraction of defective items in samples, suitable for varying sample sizes. np-Chart (Number Nonconforming): Monitors the actual count of defective items when sample sizes are constant. C-Chart (Count of Nonconformities): Used for the total number of defects per unit (e.g., scratches on a...