Table 1.
Demographics by total sample and by infant groups completing one versus two still-face trials and significance levels of tests for group differences (χ2 for frequency data and two-tailed t-tests for continuous data)
| Total sample (n=278) | Two SFP trials (n=227) | One SFP trial (n=51) | p | |
|---|---|---|---|---|
| Infant sex, female, n (%) | 133 (47.8) | 108(47.6) | 25 (49.0) | .852 |
| Infant age, weeks, M (Range) | 29.0 (25.9–35.2) | 29.2 (26.1–33.7) | 29.2 (25.9–35.2) | .388 |
| Infant race/ethnicity, n (%) | .393 | |||
| White | 85 (30.6) | 65 (28.6) | 20 (37.0) | |
| Black/Haitian | 70 (25.2) | 61 (26.9) | 12 (22.2) | |
| Hispanic | 97 (34.9) | 80 (35.2) | 17 (31.5) | |
| Other | 26 (9.4) | 21 (9.3) | 5 (9.8) | |
| Mother’s education level, n (%) | .955 | |||
| < high school | 61 (21.9) | 51 (22.5) | 10 (19.6) | |
| high school | 22 (7.9) | 17 (7.5) | 5 (9.8) | |
| some college | 60 (21.6) | 50 (22.0) | 10 (19.6) | |
| college degree | 65 (23.4) | 52 (22.9) | 13 (25.5) | |
| graduate level | 70 (25.2) | 57 (25.1) | 13 (25.5) | |
| Height, cm (M,SD) | 67.6 (2.9) | 67.6 (2.9) | 67.3 (3.2) | .453 |
| Weight, kg (M,SD) | 8.1 (0.9) | 8.1 (0.9) | 8.2 (1.0) | .883 |
| Gestational age, weeks (M,SD) | 39.1 (1.8) | 39.0 (1.8) | 39.2 (1.7) | .664 |
| Gestational weight, kg (M,SD) | 7.3 (1.2) | 7.3 (1.1) | 7.4 (1.4) | .987 |