Table 7.

Linear regression model of the variable Vickers hardness over time.

Coefficient	Estimate	Std. Error	t Value	Pr(>|t|)	Confidence	Intervals
Intercept	74.35	1.21	61.41	<0.0001	71.97	76.72
Time	−0.04597	0.01	−3.72	<0.0001	−0.07	−0.02