Process Capability Tracking
Compare period-by-period capability with consistent specification limits.
Process Capability Tracking
Browser-only calculations · No input data saved
Worked example results
| Period | Cp | Cpk | Pp | Ppk | Cpk change vs baseline |
|---|---|---|---|---|---|
| Baseline | 1.666667 | 1.333333 | 1.388889 | 1.111111 | 0 |
| Current | 2.083333 | 2.083333 | 1.851852 | 1.851852 | 0.75 |
Rounded for display only. Export includes the inputs, results, method and assumptions. Refreshing or leaving the tool clears entered data.
How to use Process Capability Tracking
- Load the worked example to see the required input format.
- Compare period-by-period capability with consistent specification limits. Use consistent units, periods and definitions.
- Select Calculate, review the assumptions and export the result for your project evidence.
Formula and method
For each period calculate Cp/Cpk using within sigma and Pp/Ppk using overall sigma; compare Cpk with the first period.
Interpretation and assumptions
Supply a justified within-subgroup sigma estimate separately from overall sample sigma. Stable, approximately normal continuous data and representative sampling are required for conventional capability interpretation. Specifications come from customer requirements, not control limits. This tracker compares entered summaries; it does not establish statistical stability or store historical records.
Results support professional judgement. They are not a certification of process stability, a financial commitment or a substitute for study design.
Frequently asked questions
How do I use the process capability tracking?
Compare period-by-period capability with consistent specification limits. Load the example first, then replace all inputs with consistent process data and select Calculate. For each period calculate Cp/Cpk using within sigma and Pp/Ppk using overall sigma; compare Cpk with the first period.
What assumptions matter for process capability tracking?
Supply a justified within-subgroup sigma estimate separately from overall sample sigma. Stable, approximately normal continuous data and representative sampling are required for conventional capability interpretation. Specifications come from customer requirements, not control limits. This tracker compares entered summaries; it does not establish statistical stability or store historical records.
Are my calculator inputs saved or sent to a server?
These native calculations run in this browser tab. Inputs are not sent to a server or saved by this calculator. Download the result if you need a record; leaving or refreshing clears the form.