Table 2.

Means and standard deviations of ΔE and roughness values

Variable		Mean	SD	SE	95% CI for Mean		Min	Max
					Lower	Upper
ΔE	Preheated	11.85	0.95	0.21	11.4	12.29	10.69	13.01
	Non-preheated	11.63	0.81	0.18	11.24	12.01	10.52	12.74
Roughness	Preheated	0.71	0.45	0.1	0.5	0.92	0.1	1.89
	Non-preheated	0.41	0.24	0.05	0.29	0.52	0.1	1.01

SD: standard deviation; SE: standard error; CI: confidence interval; Min: minimum; Max: maximum