Table 2.
Demographics of the sample.
| Baseline | 2 Year FU | p | |
|---|---|---|---|
| n | 8086 | 5957 | |
| interview_age (months), mean (SD) | 119.21 (7.52) | 143.22 (7.76) | < 0.001 |
| sex = M, n (%) | 4158 (51.4) | 3203 (53.8) | 0.006 |
| household.income, n (%) | < 0.001 | ||
| [< 50 K] | 2215 (27.4) | 1381 (23.2) | |
| [> =50 K & < 100 K] | 2311 (28.6) | 1687 (28.3) | |
| [> =100 K] | 3560 (44.0) | 2889 (48.5) | |
| high.educ, n (%) | 0.461 | ||
| < HS Diploma | 291 (3.6) | 215 (3.6) | |
| HS Diploma/GED | 599 (7.4) | 462 (7.8) | |
| Some College | 2029 (25.1) | 1421 (23.9) | |
| Bachelor | 2197 (27.2) | 1612 (27.1) | |
| Post Graduate Degree | 2970 (36.7) | 2247 (37.7) | |
| race.4level, n (%) | 0.366 | ||
| White | 5460 (68.2) | 4094 (69.3) | |
| Black | 1042 (13.0) | 714 (12.1) | |
| Asian | 171 (2.1) | 119 (2.0) | |
| Other/Mixed | 1330 (16.6) | 978 (16.6) | |
| ethnicity, n (%) | 0.269 | ||
| hisp = Yes (%) | 1583 (19.6) | 1121 (18.8) | |
| rel_group_id (twin status), n (%) | 0.847 | ||
| Singleton (1) | 7433 (91.9) | 5464 (91.7) | |
| Twin (2) | 643 (8.0) | 484 (8.1) | |
| Triplet (3) | 10 (0.1) | 9 (0.2) |
Demographic data a shown for age in months (mean, (SD)), sex at birth, household income, parental education, self-declared race, endorsement of Hispanic ethnicity and self-declared twin/triplet status (n, (%)). These factors are stratified by time point: baseline and 2-year FU. There were significant differences in income and sex at birth for those who had 2-year FU data in Release 4.0 indicative of differences in the demographics of participants as they were recruited. Participants recruited earlier in the study were more likely to have higher household income and be born male. All of these variables are controlled for in all statistical analyses to account for this. Variable names from the tabulated data release are included in the table for replication.