Table 4. Analysis of the data generated by the Plackett–Burman design.
| Coded variable |
Variable | DF | Parameter estimate | t-value | P> |t| | Significance |
|---|---|---|---|---|---|---|
| Intercept | Constant | 1 | 23.42583 | 36.69 | 0.0007 | *** |
| X1 | Glucose | 1 | 3.25917 | 5.11 | 0.0363 | * |
| X2 | Soy flour | 1 | -2.28583 | -3.58 | 0.0699 | |
| X3 | CaCl2·2H2O | 1 | 7.76250 | 12.16 | 0.0067 | ** |
| X4 | NaH2PO4 | 1 | -1.01917 | -1.60 | 0.2515 | |
| X5 | MgSO4 | 1 | 2.70250 | 4.23 | 0.0515 | |
| X6 | K2HPO4 | 1 | 1.67417 | 2.62 | 0.1198 | |
| X7 | pH | 1 | 2.38583 | 3.74 | 0.0647 | |
| X8 | Temperature | 1 | -2.81750 | -4.41 | 0.0477 | * |
| X9 | The inoculation amount | 1 | -4.42083 | -6.92 | 0.0202 | * |
Note: X1 ~ X9 represent various impact factors.
* Significant at the 0.05 level
** significant at the 0.01 level
*** significant at the 0.001 level.