RE

Control group (%)

experimental group (%)

Z

P

No

9 (15.00%)

17 (29.82%)

Level 1

Level 2

Level 3

Level 4

Occurance rate

23 (38.33%)

26 (43.33%)

2 (3.33%)

0

30 (76.92%)

22 (38.60%)

17 (29.82%)

1 (1.75%)

0

40 (70.18%)

−2.018

0.037