Table 1. Average failure load (N) of augmented and nonaugmented specimens versus tap depth.

Tap depth (mm)	Nonaugmented	Augmented	p value
0	−30.93	−40.34	<0.01
20	−22.30	−52.00	<0.01
30	−20.95	−56.82	<0.01
40	−14.87	−61.95	<0.01