Table 1.
Sample Characteristics of the Low-, Medium-, and High-Risk Groups (N = 1057)
| Low-risk group | Medium-risk group | High-risk group | F/x2, p | |
|---|---|---|---|---|
| n = 927 | n = 111 | n = 19 | ||
| Child characteristics | ||||
| Age in years, mean (SD) | 5.34 (0.34) | 5.29 (0.31) | 5.27 (0.29) | F (2,1055) = 1.55, p = .21 |
| Male, number (%) | 502 (54.15) | 51 (45.95) | 12 (63.16) | x2 = 3.56, p = .17 |
| Siblings, number (SD) | 2.06 (0.73) | 1.87 (0.73) | 1.79 (0.63) | F (2,1055) = 4.37, p < .01a |
| Parent/family characteristics | ||||
| Education mother | ||||
| University/higher professional (%) | 85.68 | 73.33 | 78.95 | x2 = 9.31, p = .010c |
| Family income (million yen) (%) | ||||
| Under 2 | 1.77 | 4.12 | 0 | x2 = 11.53, p = .31 |
| 2 or more and less than 5 | 21.32 | 28.87 | 16.67 | |
| 5 or more and less than 7 | 30.98 | 34.02 | 33.33 | |
| 7 or more and less than 10 | 30.51 | 23.71 | 44.44 | |
| 10 or more and less than 15 | 13.19 | 8.25 | 5.56 | |
| 15 or more | 2.24 | 1.03 | 0 | |
| Mother’s depression (number of “yes” answers) (%) | ||||
| 0 | 75.25 | 51.85 | 42.11 | x2 = 38.22, p = .0001c |
| 1 | 15.12 | 25.93 | 26.32 | |
| 2 | 9.64 | 22.22 | 31.58 | |
| Autistic traits (SRS), mean (SD) | ||||
| Social communication/interaction | 25.35 (8.18) | 47.66 (5.88) | 69.79 (11.25) | F(2,1055) = 634.55, p < .001a,b |
| Restricted/ repetitive behavior | 3.46 (2.55) | 9.41 (3.29) | 17.74 (4.79) | F(2,1055) = 481.47, p < .001a,b |
| Total raw score | 28.81 (9.72) | 57.07 (7.29) | 87.53 (14.49) | F(2,1055) = 738.79, p < .001a,b |
| Emotional/behavioral problems (SDQ), mean (SD) | ||||
| Emotional symptoms | 1.27 (1.43) | 2.89 (2.20) | 3.90 (3.02) | F(2,1055) = 75.13, p < .001a,b |
| Conduct problems | 1.68 (1.42) | 3.14 (1.82) | 3.42 (2.36) | F(2,1055) = 57.32, p < .001a,b |
| Hyperactivity-Inattention problems | 2.63 (1.92) | 4.74 (2.16) | 6.21 (2.52) | F(2,1055) = 83.95, p < .001a,b |
| Peer problems | 1.02 (1.12) | 2.62 (1.83) | 4.73 (1.28) | F(2,1055) = 748.49, p < .001a,b |
| Prosocial behavior | 7.13 (1.89) | 5.96 (2.03) | 4.00 (2.67) | F(2,1055) = 40.67, p < .001a,b |
| Total difficulties | 6.59 (3.92) | 13.39 (4.84) | 18.26 (5.65) | F(2,1055) = 203.90, p < .001a,b |
SD Standard deviation, SRS Social Responsiveness Scale, SDQ Strengths and Difficulties Questionnaire
a Post-hoc tests with an ANOVA showed a significant difference between the Low-risk group and the Medium-risk group (p < .05)
b Post-hoc tests with an ANOVA showed a significant difference between the Low-risk group and the High-risk group (p < .05)
c Residual analyses with a Chi-square test showed a significant difference between the Low-risk group and the other groups (p < .05)