| equation | Model summary | Parameter evaluation | |||||||
| R square | F | df1 | df2 | Significance | constant | b1 | b2 | b3 | |
| cubic curve model | 0.851 | 7.637 | 3 | 4 | 0.039 | 0.074 | −0.024 | −0.109 | −0.047 |