Table 2 ANOVA for the COD removal according to the response surface quadratic model
Source | DF | Sum of squares | Mean square | F value | P value | Â |
|---|---|---|---|---|---|---|
Model | 9 | 0.49 | 0.054 | 469.25 | < 0.0001 | Significant |
X 1 | 1 | 1.469E−003 | 1.469E−003 | 12.93 | 0.0088 |  |
X 2 | 1 | 0.29 | 0.29 | 2487.42 | < 0.0001 |  |
X 3 | 1 | 3.947E−003 | 3.947E−003 | 34.13 | 0.0006 |  |
X 1 X 2 | 1 | 5.510E−006 | 5.510E−006 | 0.048 | 0.8334 |  |
X 1 X 3 | 1 | 1.854E−004 | 1.854E−004 | 1.60 | 0.2460 |  |
X 2 X 3 | 1 | 6.487E−004 | 6.487E−004 | 5.61 | 0.0497 |  |
X 21 | 1 | 7.089E−004 | 7.089E−004 | 6.13 | 0.0425 |  |
X 22 | 1 | 0.19 | 0.19 | 1612.25 | < 0.0001 |  |
X 23 | 1 | 2.391E−003 | 2.391E−003 | 20.68 | 0.0026 |  |
Residual | 7 | 8.097E−004 | 1.157E−004 |  |  |  |
Lack of fit | 3 | 5.689E−004 | 1.896E−004 | 3.15 | 0.1483 | Not significant |
Pure error | 4 | 2.407E−004 | 6.018E−005 |  |  |  |
Cor total | 16 | 0.49 | Â | Â | Â | Â |