The calculations for the long-term statistics differ, depending on whether you specified shift or drift (variation expansion) factors for the elements and which gap specifications are given.
For calculations for short-term statistics, go to Calculations for the gap distribution (short-term statistics) for Calculate Gap Pools.
k_{i} = 1 + 8/15 |S_{i}|
k_{i} = D_{i}|
k_{i} = max{D_{i}, 1 + 8/15 |S_{i}|}
k_{i} = max{D_{i}, 1 + 8/15 |S_{i}|}
k_{i} = 1.8
Term | Description |
---|---|
C_{i} | Diametrical correction of the i^{th} element |
D_{i} | Drift factor for the i^{th} element |
N_{i} | Complexity of the i^{th} element |
S_{i} | Shift factor for the i^{th} element |
σ_{i} | Standard deviation of the i^{th} element |
σ_{adj,i} | Adjusted standard deviation of the i^{th} element |
T | Gap targeted value (if not available, T = μ_{Gap,ST}) |
T_{i} | Nominal value of the i^{th} element |
μ_{i} | Mean of the i^{th} element |
μ_{adj,i} | Adjusted mean of the i^{th} element |
V_{i} | Directional vector of the i^{th} element |
w_{i} | Allocation weight for the mean pool or the variance pool, i^{th} element |
Z.Bench_{Gap,LT} | Benchmark Z (long-term) of the gap |
Z.Bench_{Gap,ST} | Benchmark Z (short-term) of the gap |
Z.Bench_{i,LT} | Benchmark Z (long-term) of the i^{th} element |
Z.Bench_{i,ST} | Benchmark Z (short-term) of the i^{th} element |
Z_{P} | Z-value, which gives desired PPM (right tail) for long-term gap distribution |