In This Topic
Average P confidence interval
The 95% confidence interval for average P is calculated as follows:
Notation
| Term | Description |
|---|---|
| v1 | 2 * Dtot |
| v2 | 2 * (Ntot - Dtot + 1) |
| v3 | 2 * (Dtot + 1) |
| v4 | 2 * (Ntot - Dtot) |
| Dtot | Sum of all the defectives |
| Ntot | Sum of all the sample sizes |
%Defective confidence interval
The 95% confidence interval (CI) for %defective is calculated as follows:
Notation
| Term | Description |
|---|---|
| Average P | The proportion of items in your process that are defective |
PPM Defective confidence interval
The 95% confidence interval for PPM defective is calculated as follows:
Notation
| Term | Description |
|---|---|
| Average P | The proportion of items in your process that are defective |
Process Z confidence interval
The 95% confidence interval for process Z is calculated as follows:
Notation
| Term | Description |
|---|---|
 | Inverse cumulative distribution function (CDF) of a standard normal distribution |
| Average P | The proportion of items in your process that are defective |
