Table 1. Descriptive statistics.
| Demographic Characteristic | Sample used for analyses (N = 638 pairs)1 |
With missing on negative emotionality (N = 24 pairs)2 |
||
|---|---|---|---|---|
| Mean or percentage (SD) | Mean or percentage (SD) | T or chi-square | Sig. | |
| Girl* (%) | 50.3 | 41.7 | 1.4 | .24 |
| Age of mother at twin pairs birth (years) | 30.4 (4.8) | 30.5 (5.1) | .05 | .96 |
| Days premature (days) | 29.0 (17.6) | 23.9 (22.7) | -.8 | .41 |
| Weight at birth* (kg) | 2.44 (.56) | 2.72 (.60) | 2.8 | .01 |
| Mother has obtained secondary school diploma (%) | 83.1 | 70.6 | 1.8 | .18 |
| Race/Ethnicity of mother | ||||
| White/Caucasian (%) | 88.1 | 58.8 | 12.7 | <.01 |
| Family Status | ||||
| Families with less than 20 000$CAD/year (%) | 17.9 | 35.3 | 3.4 | .07 |
| Twin pairs living with both biological parents at 5 months (%) | 92.3 | 85.0 | 1.5 | .23 |
| Twin pairs living with both biological parents at 18 months (%) | 90.0 | 85.0 | .53 | .47 |
Note: Means were compared with t-test and percentages with chi-squares.
*Values compared at the individual level, all other comparisons were at the family level.
1 Actual N varies from 493 to 638 pairs because of missing data on demographic characteristics.
2 Actual N varies from 8 to 24 pairs because of missing data on demographic characteristics.