Table 3.
Design matrix and response values in Plackett–Burman factorial design.
| Source | Sum of squares | df | Mean square | F value | p value Prob > F |
|---|---|---|---|---|---|
| X1a | 7.99 | 1 | 7.99 | 1.57 | 0.2452 |
| X2a | 449.122 | 1 | 449.122 | 88.36 | <0.0001 |
| X3a | 1128.12 | 1 | 1128.12 | 221.94 | <0.0001 |
| X1a* X2a | 4.74 | 1 | 4.74 | 0.93 | 0.3624 |
| X1a* X3a | 149.51 | 1 | 149.51 | 29.41 | <0.0001 |
| X2a* X3a | 64.52 | 1 | 64.52 | 12.69 | 0.0074 |
|
| |||||
| Total error | 40.66 | 8 | 5.08 | ||
| Cor total | 1846.32 | 15 | |||
|
| |||||
| X1b | 8.57 | 1 | 8.57 | 0.29 | 0.6048 |
| X2b | 4.98 | 1 | 4.98 | 0.17 | 0.6921 |
| X3b | 7.54 | 1 | 7.54 | 0.26 | 0.6269 |
| X1b* X2b | 455.07 | 1 | 455.07 | 15.40 | 0.0044 |
| X1b* X3b | 592.31 | 1 | 592.31 | 20.05 | 0.0021 |
| X2b* X3b | 155.68 | 1 | 155.68 | 5.27 | 0.0505 |
|
| |||||
| Total error | 236.35 | 8 | 29.54 | ||
| Cor total | 1472.22 | 15 | |||
Method A: X1a (power), X2a (pressure) and X3a (time); Method B: X1b (power), X2b (temperature) and X3b (time).