Table 2.

Five level- four variable- factors experimental for FAEE.

					Levels
Variables	Units	Symbol	-2	-1		0	1	2
Reaction time	(min)	$X_1$	60	65		70	75	80
Catalyst amount	(wt.%)	$X_2$	1.5	2.0		2.5	3.0	3.5
Reaction temp.	(°C)	$X_3$	60	65		70	75	80
EtOH/OMR	(ml/ml)	$X_4$	4	5		6	7	8