Table 5.
ANOVA for response surface quadratic model for ethanol production
| Source | Sum of squares | df | Mean square | F value |
P value Prob > F |
Significant |
|---|---|---|---|---|---|---|
| Model | 54.14 | 9 | 6.02 | 5.59 | 0.0363 | Significant |
| X 1 | 18 | 1 | 18 | 16.72 | 0.0095 | |
| X 2 | 0.58 | 1 | 0.58 | 0.54 | 0.4966 | |
| X 3 | 0.07 | 1 | 0.07 | 0.065 | 0.8085 | |
| X 1X 2 | 0.57 | 1 | 0.57 | 0.53 | 0.4994 | |
| X 1X 3 | 5.41 | 1 | 5.41 | 5.02 | 0.0751c | |
| X 2X 3 | 0.69 | 1 | 0.69 | 0.64 | 0.4600 | |
| X 1 2 | 5.69 | 1 | 5.69 | 5.29 | 0.0698c | |
| X 2 2 | 22.51 | 1 | 22.51 | 20.91 | 0.0060b | |
| X 3 2 | 3.95 | 1 | 3.95 | 3.67 | 0.1136 | |
| Residual error | 5.38 | 5 | 1.08 | |||
| Lack of fit | 3.67 | 3 | 1.22 | 1.42 | 0.4377 | Not significant |
| Pure error | 1.72 | 2 | 0.86 | |||
| Correlation total | 59.52 | 14 |
P value is lower than 0.05 being regarded as significant; otherwise, it is considered as not significant. P value is close to 0.05, model P < 0.05, lack of fit P > 0.05, R2 = 0.9096, adj-R2 = 0.7468, CV% = 19.87, SD = 1.04, mean = 5.22, Pred R2 = − 0.054, Adeq precisior = 8.421, Press = 62.52