Coded and actual variables and their level in CCD
| Code . | Variable . | levels . | ||
|---|---|---|---|---|
| (−1) . | (0) . | (+1) . | ||
| A | Initial dye concentration (mg/L) | 10 | 30 | 50 |
| B | pH | 3 | 7 | 11 |
| C | Dose (g/L) | 4 | 8 | 12 |
| D | Contact time (min.) | 10 | 65 | 120 |
| Code . | Variable . | levels . | ||
|---|---|---|---|---|
| (−1) . | (0) . | (+1) . | ||
| A | Initial dye concentration (mg/L) | 10 | 30 | 50 |
| B | pH | 3 | 7 | 11 |
| C | Dose (g/L) | 4 | 8 | 12 |
| D | Contact time (min.) | 10 | 65 | 120 |