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

Table 10

Estimated regression coefficients for wear rate.

Term	Coef	SE Coef	-ratio	value
Constant	−0.783168	0.625581	−1.252	0.299
Speed	0.008006	0.004209	1.902	0.153
Load	0.117524	0.052127	2.255	0.109
Volume composition	−0.012697	0.022237	−0.571	0.608
Speed speed	−0.000009	0.000008	−1.085	0.357
Load load	0.000042	0.001946	0.022	0.984
Volume composition volume composition	0.002760	0.000954	2.894	0.063
Speed load	−0.000392	0.000144	−2.718	0.073
Speed volume composition	−0.000068	0.000101	−0.673	0.549
Load volume composition	0.001647	0.000944	1.745	0.179