Table 3. Analysis of variance for the fitted response surface quadratic model.
| Source | Sum of squares | DF | Mean square | F-value | P-value |
|---|---|---|---|---|---|
| Model | 0.11 | 14 | 8.105E ‒ 03 | 4.46 | 0.0042 |
| X1: Ultrasonic power | 8.167E ‒ 06 | 1 | 8.167E ‒ 06 | 4.498E ‒ 03 | 0.9475 |
| X2: Extraction temperature | 1.242E ‒ 04 | 1 | 1.242E ‒ 04 | 0.068 | 0.7975 |
| X3: Liquid/solid ratio | 0.018 | 1 | 0.018 | 9.95 | 0.0070 |
| X4: Ultrasonic time | 0.011 | 1 | 0.011 | 5.96 | 0.0285 |
| X1 × X2 | 3.788E ‒ 03 | 1 | 3.788E ‒ 03 | 2.09 | 0.1706 |
| X1 × X3 | 2.186E ‒ 03 | 1 | 2.186E ‒ 03 | 1.20 | 0.2911 |
| X1 × X4 | 1.071E ‒ 04 | 1 | 1.071E ‒ 04 | 0.059 | 0.8116 |
| X2 × X3 | 5.546E ‒ 04 | 1 | 5.546E ‒ 04 | 0.31 | 0.5892 |
| X2 × X4 | 2.401E ‒ 05 | 1 | 2.401E ‒ 05 | 0.013 | 0.9101 |
| X3 × X4 | 1.346E ‒ 04 | 1 | 1.346E ‒ 04 | 0.074 | 0.7894 |
| X12 | 5.629E ‒ 05 | 1 | 5.629E ‒ 05 | 0.031 | 0.8628 |
| X22 | 0.072 | 1 | 0.072 | 39.88 | < 0.0001 |
| X32 | 8.317E ‒ 03 | 1 | 8.317E ‒ 03 | 4.58 | 0.0504 |
| X42 | 6.343E ‒ 03 | 1 | 6.343E ‒ 03 | 3.49 | 0.0827 |
| Residual | 0.025 | 14 | 1.816E ‒ 03 | ||
| Lack of fit | 0.023 | 10 | 2.340E ‒ 03 | 4.63 | 0.0765 |
| Pure error | 2.023E ‒ 03 | 4 | 5.057E ‒ 04 | ||
| Cor total | 0.14 | 28 | |||
| R2 = 0.8170 | |||||
| Adj R2 = 0.6339 | |||||
| Adeq precision = 6.952 | |||||
| CV(%) = 20.19 |