Table 3.

ANOVA table for drill roughness, drill speed, and drilling depth.

Method
Factor coding	(− 1, 0, + 1)

Factor information
Factor	Type	Levels	Values
Drill roughness	Fixed	5	1, 2, 3, 4, 5
Drill speed	Fixed	5	1000, 1500, 2000, 2500, 3000
Drill depth	Fixed	5	3, 4, 5, 6, 7

Analysis of variance
Source	DF	Adj SS	Adj MS	F-value	P-value
Drill roughness	4	0.035878	0.008969	4.98	0.003
Drill speed	4	0.004574	0.001143	0.63	0.641
Drill depth	4	0.414524	0.103631	57.53	0.000
Error	32	0.057641	0.001801
Total	44	0.513712

Model summary
S	R-sq	R-sq(adj)	R-sq(pred)
0.0424414	88.78%	84.57%	77.81%

Regression equation
GRG = 1.0377 − 0.08842 drill depth − 0.000011 drill speed − 0.01696 drill roughness