Table 1.
Characteristics of Manitoba birth cohorts (1978–1982, 1984–1987) and study sample
| Variable | Format | Birth cohort members | Siblings in families with at least one same-sex pair | Study sample of same-sex sibling pairs* |
|---|---|---|---|---|
| Place of Residence and Age |
|
|
|
|
| Winnipeg |
Percent |
47.7 |
40.9 |
39.5 |
| Age at Jan 1, 2000 |
Mean (SD) |
16.8 (3.02) |
16.9 (2.85) |
16.8 (2.83) |
| Family Variables |
|
|
|
|
| Maternal age at first birth |
Mean (SD) |
23.2 (4.55) |
22.7 (4.24) |
22.9 (4.25) |
| Number of residential moves between child’s age 8 and 17.5 |
Mean (SD) |
0.87 (1.45) |
0.84 (1.49) |
0.79 (1.40) |
| Birth order |
Mean (SD) |
2.02 (1.16) |
2.35 (1.36) |
2.35 (1.35) |
| Number of children in family |
Mean (SD) |
3.05 (1.55) |
3.76 (1.80) |
3.63 (1.74) |
| Mother married at birth of child |
Percent |
81.5 |
84.7 |
87.1 |
| Months in which family received income assistance between child’s age 8 and 17.5 |
Mean (SD) |
5.07 (19.11) |
4.98 (18.96) |
4.43 (17.89) |
| Continuous Outcomes |
|
|
|
|
| Language Arts Index (scaled logit) |
Mean (SD) |
0.00 (1.00) |
-0.08 (1.03) |
-0.04 (1.01) |
| Health Status (ADG Morbidity Score) (age 12–17) |
Mean (SD) |
9.69 (6.45) |
9.08 (6.26) |
9.11 (6.24) |
| Hospital and Physician Costs (age 12–17, C$1993) |
Mean (SD) |
1,158 (4,661) |
1,164 (5,315) |
1,137 (5,091) |
| Binary Outcomes |
|
|
|
|
| Not in Grade 12 at Appropriate Age |
Percent |
28.7 |
32.4 |
30.6 |
| Teenage Pregnancy (females to age 19) |
Percent |
13.1 |
14.4 |
13.5 |
| Received Income Assistance (age 18–19) |
Percent |
5.7 |
5.8 |
5.3 |
| Number of Boys |
|
54,056 |
20,391 |
15,660 |
| Number of Girls |
|
51,382 |
18,649 |
14,012 |
| Number of Families | 71,126 | 16,060 | 14,502 |
* 334 families contributed a sibling pair of both sexes, so the total number of pairs used in the sibling/neighborhood analysis was 14,836.
The calculations for "maternal age at first birth", "number of children in family", and "birth order" were based on files which go back to 1970 for the mother. This leads to a slight overestimate of maternal age at first birth and a slight underestimate of the other two variables (since a few children will have been born before 1970). Twins were excluded from birth cohorts and samples. Birth cohort members included those born in and remaining in the province between birth and age 17.5.