Table 4.
Mean Improvement in VAS for Back Pain Scores and P Values
| Ranks | ||||
|---|---|---|---|---|
| N | Mean Rank | Sum of Ranks | ||
| VAS back (postop) − VAS back (preop) | Negative ranks | 80a | 42.11 | 3327.00 |
| Positive ranks | 4b | 39.75 | 159.00 | |
| Ties | 6c | |||
| Total | 90 | |||
| Test Statisticsd | ||||
| VAS Back (Postop) − VAS Back (Preop) | ||||
| Z | −7.365e | |||
| Asymptotic significance (2-tailed) | .000 | |||
Abbreviations: VAS, visual analogue score; preop, preoperative; postop, postoperative.
a VAS back (postop) < VAS back (preop).
b VAS back (postop) > VAS back (preop).
c VAS back (postop) = VAS back (preop).
d Wilcoxon signed rank test.
e Based on positive ranks.