Table 2.
Subject characteristics
| Characteristic | Responders (n = 3539) | Nonresponders (n = 21974) |
| Age | ||
| Mean (SD) | 40.6 (6.2) | 41.0 (6.4) |
| Range | 18–64 | 19–76 |
| Female sex | 3298 (93.2) | 20263 (92.2) |
| Race/ethnicity* | ||
| White | 3045 (89.7) | 18507 (84.2) |
| Black/African-American | 136 (4.0) | 1098 (5.0) |
| Hispanic | 79 (2.3) | 703 (3.2) |
| Asian/Pacific Islander | 21 (0.6) | 171 (0.8) |
| Native American | 38 (1.1) | 316 (1.4) |
| Mixed/other | 77 (2.3) | 520 (2.4) |
| Unknown | 0 | 559 (2.5) |
| Declined to answer | 0 | 100 (0.5) |
| Education level† | ||
| Did not complete high school | 55 (1.6) | 706 (3.2) |
| High school degree | 555 (15.7) | 4366 (19.9) |
| Some college | 1391 (39.3) | 9074 (41.3) |
| College degree | 991 (28.0) | 5179 (23.6) |
| Some graduate school or degree | 543 (15.4) | 2568 (11.7) |
| Unknown | 0 | 81 (0.4) |
| Annual household income‡ | ||
| <$15000 | 107 (3.5) | 868 (3.9) |
| $15000$24999 | 262 (8.6) | 1983 (9.0) |
| $25000–$34999 | 410 (13.4) | 2945 (13.4) |
| $35000–$49999 | 665 (21.7) | 4177 (19.0) |
| $50000–$74999 | 806 (26.3) | 5065 (23.0) |
| $75000–$99999 | 406 (13.3) | 2003 (9.1) |
| $100000–$149999 | 220 (7.2) | 1442 (6.6) |
| $150000–$199999 | 85 (2.8) | 273 (1.2) |
| $200000–$249999 | 61 (2.0) | 117 (0.5) |
| ≥ $250000 | 16 (0.5) | 103 (0.5) |
| Declined to answer | 24 (0.8) | 1 (0.0) |
| Unknown | 0 | 2997 (13.6) |
| Employment status § | ||
| Employed full-time | 1766 (80.0) | 9070 (42.2) |
| Employed part-time | 554 (15.7) | 2355 (11.0) |
| Self-employed | 281 (7.9) | 1588 (7.4) |
| Not employed but looking for work | 119 (3.4) | 852 (4.0) |
| Not employed and not looking for work | 70 (2.0) | 588 (2.7) |
| Retired | 40 (1.1) | 258 (1.2) |
| Student | 149 (4.2) | 3071 (14.3) |
| Homemaker | 974 (27.5) | 3566 (16.6) |
| Disabled | 0 | 138 (0.6) |
| Not sure | 4 (0.1) | 0 |
| Declined to answer | 4 (0.1) | 0 |
| Not applicable | 0 | 0 |
| Number of children in household | ||
| Mean (SD) | 1.9 (1.0) | 1.9 (1.2) |
| Range | 0–9 | 0–15 |
| Country of residence | ||
| Australia | 2 (0.1) | -- |
| Canada | 2 (0.1) | -- |
| United States | 3535 (99.9) | -- |
Values are reported as number (percentage) unless otherwise indicated.
*There were 143 missing responses for this variable.
† There were 4 missing responses for this variable.
‡ There were 477 missing responses for this variable.
§ Responses sum to more than 100% because respondents could select more than one answer. Nonresponders did not have this option. There were 488 missing responses for this variable.