Table 1 Demographic characteristics of the sample, n(%)
|  | B-LBC | O-LBC | N-LBC | F or χ2 | p value |
|---|---|---|---|---|---|
Gender | Â | Â | Â | 0.24 | 0.888 |
 Male | 380 (55.0) | 298 (54.7) | 394 (53.8) |  |  |
 Female | 311 (45.0) | 247 (45.3) | 339 (46.2) |  |  |
Age, mean (SD) | 13.1 (1.2) | 13.2 (1.2) | 13.1 (1.2) | 2.57 | 0.076 |
Grade | Â | Â | Â | 6.52 | 0.038 |
 Grade5 Grade6 | 323 (46.2) | 215 (39.0) | 316 (42.7) |  |  |
 Grade7 Grade8 | 376 (53.8) | 336 (61.0) | 424 (57.3) |  |  |
Perceived income level | Â | Â | Â | 12.69 | 0.013 |
 Much better off/better off | 193 (27.8) | 124 (22.6) | 205 (28.0) |  |  |
 The same | 455 (65.7) | 363 (66.2) | 471 (64.3) |  |  |
 Poorer/much poorer | 45 (6.5) | 61 (11.1) | 57 (7.8) |  |  |
Any sibling | Â | Â | Â | 2.54 | 0.281 |
 Yes | 249 (35.6) | 182 (33.0) | 235 (31.7) |  |  |
 No | 450 (64.4) | 370 (67.0) | 506 (68.3) |  |  |