Table 1.

The estimated mean and 95% confidence intervals for each performance measure assessed at pre- and post-test for the skill test in Study 2.

Performance measure	Time	Low CI	Moderate CI	Δ
Serves-in (%)	Pre-test	31.7% (26.1%, 37.5%)	29.9% (24.6%, 36.7%)	-1.6% (-9.7%, 9.2%,)
	Post-test	35.2% (29.1%, 41.6%)	31.2% (25.7%, 37.1%)	-3.3% (-10.7%, 6.9%)
	Δ	3.6% (-41.6%, 15.6%)	1.3% (-7.1%, 11.9%)
Service displacement from the T (cm)	Pre-test	108.9 (93.6, 124.1)	82.6 (67.3, 97.9)	-26.3 (-55.2, 2.7)
	Post-test	68.2 (52.0, 84.3)	79.4 (63.7, 95.2)	11.3 (-18.9, 41.5)
	Δ	-40.7 (-63.5, -17.9)	-3.2 (-25.6, 19.3)
Service velocity (kph)	Pre-test	129.0 (123.7, 134.3)	133.2 (128.0, 138.5)	4.3 (-6.0, 14.5)
	Post-test	131.3 (126.1, 136.7)	133.0 (127.7, 138.3)	1.7 (-8.6, 11.9)
	Δ	2.4 (1.0, 3.8)	-0.2 (-1.5, 1.0)

Δ denotes the estimated difference between pre- and post-test for each group or the difference between each practice group at pre-test and post-test.