Control chart vs run chart: median line versus 3-sigma control limits, how many data points each needs, and which to use at each project stage.
Cp shows potential capability, Cpk shows what you actually make. The gap reveals off-centering you can fix for free, with a worked example and verdict.
X-bar R or X-bar S chart? The deciding input is subgroup size. Why the range loses efficiency as n grows, with a worked example and a verdict by role.
c-chart vs u-chart: when each attribute chart fits, constant vs variable inspection units, 3-sigma Poisson control limits, and a clear verdict.
EWMA vs CUSUM control charts: how each detects small process shifts Shewhart misses, ARL comparison, design parameters, and which to pick.
CUSUM vs Shewhart charts for small shift detection: 1-sigma shift takes 44 subgroups on Shewhart vs 10 on CUSUM. Decision framework + EWMA middle ground.
Step-by-step calculation of p-chart control limits with a worked PCB inspection example. Covers the variable sample size problem (exact, average-n, and standardized approaches), the np>=5 minimum, and the Laney p-prime chart for overdispersion.
When and how to use the I-MR (Individual Moving Range) control chart. Covers the five scenarios requiring individual charts, a complete worked example with control limit formulas (d2=1.128, D4=3.267), normality assumptions, and sensitivity comparison vs. X-bar R.
Decision tree for selecting the correct SPC control chart type. Covers variable vs. attribute data, subgroup size thresholds, p-chart and c-chart distribution requirements, CUSUM and EWMA alternatives, and common chart-type mismatches with real consequences.
Comparison of Cpk and Ppk process capability indices with worked example, formulas, and a decision table for which index to report in PPAP submissions, customer audits, and ongoing SPC monitoring. Includes diagnostic use of the Cpk-Ppk gap.
Decision framework for selecting between Western Electric Rules (4 tests, 1956) and Nelson Rules (8 tests, 1984) on SPC control charts. Covers false alarm rates, pattern recognition examples, and how to map each rule type to your reaction plan.
Step-by-step worked example for building an X-bar and R control chart from CNC manufacturing data. Includes A2, D3, D4 constants for n=5, control limit formulas, pattern rule application, and Cpk calculation.