Table 2.

The statistical differences between optimal and suboptimal drilling parameter groups.

Drilling parameters		Temperatures	Time
Optimal, regarding temperatures & time	Mean	1.06A	0.97a
	N	96	96
	Std. Deviation	0.48	0.45
Suboptimal, because of temperatures	Mean	4.40B	0.57b
	N	72	72
	Std. Deviation	1.36	0.41
Suboptimal, because of time	Mean	0.54C	5.92c
	N	24	24
	Std. Deviation	0.28	8.02
Total	Mean	2.32	2.04
	N	192	192
	Std. Deviation	1.99	4.59

Abbreviations: different capitals and lower cases indicate statistical differences between means. Kruskal-Wallis test, pairwise comparisons, p<0.05.