Step index | Experimental group (n = 1020) | χ2 | Control group (n = 1112) | χ2 | χ2 | |||
a1) | b2) | a3) | b4) | 1) 3) | 2) 4) | |||
Qualified | 861 | 911 | 10.739* | 920 | 926 | 0.115 | 1.089 | 16.281* |
Unqualified | 159 | 109 | 192 | 186 |