The Application of Response Surface Methodology in the Investigation of the Tribological Behavior of Palm Cooking Oil Blended in Engine Oil

Table 8

Estimated regression coefficients for COF.

Term	Coef	SE Coef	-ratio	value
Constant	0.337598	0.077232	4.371	0.022
Speed	−0.000174	0.000520	−0.335	0.760
Load	−0.064568	0.006435	−10.033	0.002
Volume composition	0.005517	0.002745	2.010	0.138
Speed speed	0.000002	0.000001	1.571	0.214
Load load	0.004496	0.000240	18.712	0.000
Volume composition volume composition	0.000039	0.000118	−2.790	0.761
Speed load	−0.000050	0.000018	−2.790	0.068
Speed volume composition	−0.000033	0.000012	−2.667	0.076
Load volume composition	0.000236	0.000117	2.023	0.136