Term Coefficienta Viscosity Overall acceptability
Intercept ao 550.47 7.45
X1 (type of plant) a1 -14.67 -0.17
X2 (plant ratio) a2 -115.50* -0.75**
X1X2 a12 30 0.035
  R2 0.8877 0.5417
  F 15.8 2.36
  Sig F 0.003 0.1702
  S.E. 49.48 0.82
  Adeq precision 9.299 3.532
aY = a0 + a1X1 + a2X2 + a12X1X2
* Significant at p ≤ 0.05
**Significant at p ≤ 0.01
Table 8: Response model constants and regression analysis for viscosity and overall acceptability.