. 2016 Sep 29;11(9):e0163452. doi: 10.1371/journal.pone.0163452

Table 4. Summary statistics of the actual operative window according to size for each level ( $\bar{x}$ ± S, cm).

Actual operative Window		L1-2	L2-3	L3-4	L4-5	L5-S1
<1 cm	Male	0.85 ± 0.12 (2^*) (0.76–0.93)				0.17 ± 0.64 (11^*) (0.00–0.89)
	Female				0.84 ± 0.11 (4^*) (0.68–0.93)	0.66 ± 0.33 (6^*) (0.00–0.89)
	P					0.000
≥1 cm	Male	1.98 ± 0.49 (28^*) (1.26–3.18)	2.48 ± 0.56 (30^*) (1.58–3.80)	2.80 ± 0.60 (30^*) (1.87–4.18)	2.51 ± 0.61 (30^*) (1.40–3.62)	2.06 ± 0.52 (19^*) (1.04–3.02)
	Female	1.69 ± 0.27 (30^*) (1.21–2.41)	2.08 ± 0.44 (30^*) (1.40–3.48)	2.22 ± 0.33 (30^*) (1.58–2.90)	1.62 ± 0.42 (26^*) (1.06–2.98)	2.09 ± 0.43 (24^*) (1.28–2.91)
	P	0.008	0.003	0.000	0.000	0.800

* Note:The number of samples.

Table 4. Summary statistics of the actual operative window according to size for each level (x¯ ± S, cm).