| Variable | County-Level (Rural and Urban) Variables for Randomization (n = 16) | Differences in Raw Variables Between Study Groups* | ||
|---|---|---|---|---|
| Mean (SD) | Minimum, Maximum | Optimal Randomizations (n = 14) | Remaining Randomizations (n = 126) | |
| In CIIS (%)† | 87.2 (7.7) | 70, 100 | <1 (1) | <1 (1) |
| Children aged 19–35 months, by county (n) | 4,197 (4,432) | 234, 12,354 | 223 (613) | 1,264 (6,325)‡ |
| Up to date at baseline (%) | 40.8 (8.3) | 27.0, 54.0 | 2.1 (5.0) | 4.9 (15.0)‡ |
| Hispanic ethnicity (%)§ | 22.3 (12.9) | 6.0, 44.0 | 5.6 (11.3) | 7.9 (23.3) |
| African American race‖ | 2.9 (2.7) | 0, 10.0 | <1 (1.0) | 1.4 (4.5) |
| Average income ($)¶ | 53,481 (15,793) | 29,738, 93,819 | 3,659 (9,702) | 9,731 (27,131)‡ |
| Pediatric–to–Family Medicine practices ratio | 0.28 (0.25) | 0, 1.0 | 0.20 (0.40) | 0.15 (0.40) |
| CHCs (n) | 4.4 (3.5) | 0, 11 | 1.3 (2.8) | 1.6 (4.8) |
Data are based on baseline information on the counties from the Colorado Department of Public Health and Environment, the Colorado Immunization Information System (CIIS), and 2010 Census data.
↵* Data are means (maximums).
↵† Percentage of children between 0 and 4 years who had ≥2 immunization records in CIIS.
↵‡ P < .01, optimal vs remaining randomizations.
↵§ Population by ethnicity (Hispanic/Latino or not).
↵‖ Population by race (black or other).
↵¶ Population by income.
CHC, community health center; SD, standard deviation.