Cp
Notation
| Term | Description |
|---|---|
| USL | Upper specification limit |
| LSL | Lower specification limit |
| Toler | Multiplier of the sigma tolerance (Minitab uses 6 as the default value) |
 | Between/within standard deviation |
Cpk
PPM Total for expected "between/within" performance
The expected number of parts per million that are outside of the specification limits, based on the variation between/within subgroups, is
Notation
| Term | Description |
|---|---|
| PPM | Parts per million |
| LSL | Lower specification limit |
| USL | Upper specification limit |
| Φ (X) | Cumulative distribution function (CDF) of a standard normal distribution |
 | Average of the observations |
| s | Between/within subgroup standard deviation |
Z.LSL Z.USL Z.Bench - B/W
Benchmark Z statistics for between/within capability are calculated by finding the Z value using the standard normal (0,1) distribution for the corresponding statistics.
where:
Notation
| Term | Description |
|---|---|
| LSL | Lower specification limit |
| USL | Upper specification limit |
| Φ (X) | Cumulative distribution function (CDF) of a standard normal distribution |
| Φ-1 (X) | Inverse CDF of a standard normal distribution |
 | Between/within standard deviation |
