highly significantp < 0.01
Examination of these coefficients with a T -test shows that the FFA% ( Y ), linear, square and interaction terms of ethanolic KOH ( X 1 ) were highly significant ( p < 0.01), and that the linear terms of reaction temperature°C ( X 2 ) were highly significant ( p < 0.01), while the reaction time (X 3 ) was significant at p < 0.05.