Table 2.
Test of significance for regression coefficient a.
| Source | Sum of squares | Degree of freedom | Mean square | F-value | p-value |
|---|---|---|---|---|---|
| Model b | 2652.90 | 9 | 294.77 | 389.49 | <0.0001 |
| X1 | 16.41 | 1 | 16.41 | 21.69 | 0.0023 |
| X2 | 10.86 | 1 | 10.86 | 14.36 | 0.0068 |
| X3 | 254.26 | 1 | 254.26 | 335.97 | <0.0001 |
| X1X2 | 12.42 | 1 | 12.42 | 16.41 | 0.0049 |
| X1X3 | 60.24 | 1 | 60.24 | 79.60 | <0.0001 |
| X2X3 | 0.85 | 1 | 0.85 | 1.12 | 0.3249 |
| X12 | 804.65 | 1 | 804.65 | 1063.23 | <0.0001 |
| X22 | 1052.30 | 1 | 1052.30 | 1390.46 | <0.0001 |
| X32 | 224.08 | 1 | 224.08 | 296.09 | <0.0001 |
| Residual | 5.30 | 7 | 0.76 | ||
| Lack of Fit | 2.90 | 3 | 0.97 | 1.61 | 0.3207 |
| Pure Error | 2.40 | 4 | 0.60 | ||
| Cor Total | 2658.19 | 16 | |||
|
| |||||
| Pred R2 | 0.981 | ||||
| Adj R2 | 0.995 | ||||
| Adeq Precision | 50.947 | ||||
a
The results were obtained with the Design Expert 7.0 software;
b
X1 is ultrasound time (min), X2 is solid–liquid ratio (g/mL), X3 is ultrasound power (W).