Table 1. Descriptive Statistics of the Study Sample (Year = 2009).
| Variables | All | Quantiles | ||||
|---|---|---|---|---|---|---|
| Mean(SD)/Frequency(%) | 10th quant. | 25th quant. | Median | 75th quant. | 90th quant. | |
| N | 2225 | 674 | 439 | 538 | 347 | 227 |
| Academic Performance Scores | 17.94(4.13) | 13.15 (2.45) | 17.10 (0.83) | 19.71 (0.45) | 22.19 (1.11) | 25 (0.00) |
| Primary Regressors of Interest | ||||||
| VIPA | 2.25 (2.16) | 2.34 (2.12) | 2.07 (2.20) | 2.02 (2.08) | 2.64 (2.28) | 2.28 (2.13) |
| MoIPA | 3.09 (2.37) | 2.80 (2.42) | 3.24 (2.27) | 3.07 (2.32) | 3.67 (2.38) | 2.86 (2.35) |
| MiIPA | 5.23 (2.43) | 4.87 (2.64) | 5.30 (2.43) | 5.45 (2.28) | 5.47 (2.24) | 5.31 (2.27) |
| Demographic and Socioeconomic Characteristics | ||||||
| Age | 10.33 (0.61) | 10.33(0.89) | 10.32 (0.39) | 10.34 (0.54) | 10.31 (0.37) | 10.37 (0.39) |
| Gender | ||||||
| Boys | 1052(49.44%) | 357 (55.61%) | 216 (51.67%) | 231 (44.94%) | 159 (47.46%) | 89 (40.64%) |
| Girls | 1076(50.56%) | 285 (44.39%) | 202 (48.33%) | 283 (55.06%) | 176 (52.54%) | 130 (59.36%) |
| Household Income Per Capita Per Month | ||||||
| <¥1500 | 416 (19.78%) | 155 (24.56%) | 83 (19.90%) | 98 (19.33%) | 43 (12.99%) | 37 (17.05%) |
| ¥1500–2500 | 516 (24.54%) | 164 (25.99%) | 110 (26.38%) | 121 (23.87%) | 64 (19.34%) | 57 (26.27%) |
| >¥2500 | 1171(55.68%) | 312 (49.45%) | 224 (53.72%) | 288 (56.80%) | 224 (67.67%) | 123 (56.68%) |
| Family Structure | ||||||
| Single-parent | 115 (5.42%) | 47 (7.34%) | 28 (6.71%) | 17 (3.32%) | 11 (3.28%) | 12 (5.53%) |
| Nuclear family | 1272(59.97%) | 386 (60.31%) | 241 (57.79%) | 307 (59.96%) | 212 (63.28%) | 126 (58.06%) |
| Extended family | 734 (34.61%) | 207 (32.34%) | 148 (35.49%) | 188 (36.72%) | 112 (33.43%) | 79 (36.41%) |
| Mother’s educational attainment | ||||||
| Less than high school | 524 (24.80%) | 203 (31.92%) | 107 (25.72%) | 124 (24.36%) | 48 (14.37%) | 42 (19.27%) |
| High school | 592 (28.02%) | 223 (35.06%) | 123 (29.57%) | 123 (24.17%) | 74 (22.16%) | 49 (22.48%) |
| College and above | 997 (47.18%) | 210 (33.02%) | 186 (44.71%) | 262 (51.47%) | 212 (63.47%) | 127 (58.26%) |
| Father’s educational attainment | ||||||
| Less than high school | 422 (19.98%) | 166 (26.06%) | 95 (22.89%) | 96 (18.75%) | 37 (11.11%) | 28 (13.02%) |
| High school | 645 (30.54%) | 225 (35.32%) | 131 (31.57%) | 158 (30.86%) | 75 (22.52%) | 56 (26.05%) |
| College and above | 1045(49.48%) | 246 (38.62%) | 189 (45.54%) | 258 (50.39%) | 221 (66.37%) | 131 (60.93%) |
| Time spent on other activities | ||||||
| Attend Extracurricular Activities? | ||||||
| Yes | 1443(67.62%) | 364 (57.23%) | 276 (64.64%) | 367 (71.26%) | 268 (79.29%) | 168 (77.06%) |
| No | 691 (32.38%) | 272 (42.77%) | 151 (35.36%) | 148 (28.74%) | 70 (20.71%) | 50 (22.94%) |
| Average Time Spent on Homework Per Day | ||||||
| < 1 hour | 188 (8.79%) | 28 (4.33%) | 33 (7.80%) | 47 (9.16%) | 52 (15.38%) | 28 (12.79%) |
| 1–2 hours | 947 (44.25%) | 211 (32.61%) | 191 (45.15%) | 258 (50.29%) | 163 (48.22%) | 124 (56.62%) |
| 2–3 hours | 761 (35.56%) | 291 (44.98%) | 147 (34.75%) | 172 (33.53%) | 96 (28.40%) | 55 (25.11%) |
| > 3 hours | 244 (11.40%) | 117 (18.08%) | 52 (12.29%) | 36 (7.02%) | 27 (7.99%) | 12 (5.48%) |
| Health Status | ||||||
| Weight Status | ||||||
| Obese | 194 (11.18%) | 72 (13.38%) | 32 (9.30%) | 52 (12.47%) | 22 (8.49%) | 16 (9.04%) |
| Not Obese | 1541(88.82%) | 466 (86.62%) | 312 (90.70%) | 365 (87.53%) | 237 (91.51%) | 161 (90.96%) |
| Having Chronic Allergic Rhinitis? | ||||||
| Yes | 330 (15.49%) | 95 (14.87%) | 64 (15.02%) | 69 (13.45%) | 71 (21.19%) | 31 (14.22%) |
| No | 1801(84.51%) | 544 (85.13%) | 362 (84.98%) | 444 (86.55%) | 264 (78.81%) | 187 (85.78%) |
| Having Asthma? | ||||||
| Yes | 93 (4.36%) | 27 (4.21%) | 13 (3.07%) | 19 (3.69%) | 18 (5.39%) | 16 (7.31%) |
| No | 2041(95.64%) | 615 (95.79%) | 411 (96.93%) | 496 (96.31%) | 316 (94.61%) | 203 (92.69%) |
Note: Missing values for Academic performance scores were 60 (percent of missing = 2.70%), for age were 74 (percent of missing = 3.33%), for gender were 97 (percent of missing = 4.36%), for household income were 122 (percent of missing = 5.48%), for family structure were 104 (percent of missing = 4.67%), for mother’s education were 112 (percent of missing = 5.03%), for father’s education were 113 (percent of missing = 5.08%), for attending extracurricular activities were 91 (percent of missing = 4.09%), for average time spent on homework were 85 (percent of missing = 3.82%), for weight status were 490 (percent of missing = 22.02%), for rhinitis were 94 (percent of missing = 4.22%) and for asthma were 91 (4.09%).