Demographic characteristics of the sample
| Group | n (%) | Intervention group | Control group | χ2 | p Value |
| n (%) | n (%) | ||||
| Age in years | |||||
| 21 | 77 (10.1) | 17 (4.0) | 60 (17.8) | 220.00 | p<0.01 |
| 21 | 174 (22.8) | 42 (9.9) | 132 (39.1) | ||
| 22 | 188 (24.6) | 93 (21.8) | 95 (28.1) | ||
| 23 | 195 (25.5) | 156 (36.6) | 39 (11.5) | ||
| 24+ | 130 (17.0) | 118 (27.7) | 12 (3.6) | ||
| Gender | |||||
| Male | 339 (44.4) | 191 (44.8) | 148 (43.8) | 0.78 | p>0.05 |
| Female | 425 (55.6) | 235 (55.2) | 190 (56.2) | ||
| Race | |||||
| Han | 714 (93.5) | 391 (91.8) | 323 (95.6) | 4.40 | p<0.05 |
| Other | 50 (6.5) | 35 (8.2) | 15 (4.4) | ||
| Region of origin | |||||
| Northeast | 90 (11.8) | 32 (7.5) | 58 (17.2) | 72.17 | p<0.01 |
| North | 122 (16.0) | 63 (14.8) | 59 (17.5) | ||
| Northwest | 86 (11.3) | 57 (13.4) | 29 (8.6) | ||
| East | 145 (19.0) | 69 (16.2) | 76 (22.5) | ||
| South | 252 (33.0) | 184 (43.2) | 68 (20.1) | ||
| Southwest | 26 (3.4) | 9 (2.1) | 7 (5.0) | ||
| Middle South | 43 (5.6) | 12 (2.8) | 31 (9.2) | ||
| Expenditure per month (RMB) | |||||
| 400 | 238 (31.2) | 71 (16.7) | 60 (17.8) | 7.91 | p>0.05 |
| 400–599 | 214 (28.0) | 170 (39.9) | 155 (45.9) | ||
| 600–799 | 118 (15.4) | 116 (27.2) | 63 (18.6) | ||
| 800+ | 194 (25.4) | 69 (16.2) | 60 (17.8) | ||
| Paternal education | |||||
| Elementary school | 80 (10.5) | 52 (12.2) | 28 (8.3) | 16.56 | p<0.01 |
| Junior high school | 192 (25.1) | 124 (29.1) | 68 (20.1) | ||
| High school | 311 (40.7) | 167 (39.2) | 144 (42.6) | ||
| College and above | 181 (23.7) | 83 (19.5) | 98 (29.0) | ||
| Maternal education | |||||
| Elementary school | 166 (21.7) | 100 (23.5) | 66 (19.5) | 11.63 | p<0.01 |
| Junior high school | 225 (29.5) | 140 (32.9) | 85 (25.1) | ||
| High school | 261 (34.2) | 135 (31.7) | 126 (37.3) | ||
| College and above | 112 (14.7) | 51 (12.0) | 61 (18.0) | ||
| Paternal occupation | |||||
| Operations and commercial | 520 (68.1) | 301 (70.7) | 219 (64.8) | 3.14 | p>0.05 |
| Staff | 188 (24.6) | 95 (22.3) | 93 (27.5) | ||
| Technical and teaching | 56 (7.3) | 30 (7.0) | 26 (7.7) | ||
| Maternal occupation | |||||
| Operations and commercial | 562 (73.6) | 329 (77.2) | 233 (68.9) | 7.40 | p<0.05 |
| Staff | 133 (17.4) | 61 (14.3) | 72 (21.3) | ||
| Technical and teaching | 69 (9.0) | 36 (8.5) | 33 (9.8) | ||