Table 3.
Average travel time, and parameters in the log-logistic function in the gravity model by geographic areas and calendar seasons
| No. patients | T_alla | T_60b | μ | α | σ | θ | β | |
|---|---|---|---|---|---|---|---|---|
| All ZIP code areas | 2,376,743 | 17.6 | 13.3 | 0.20 | 0.66 | 0.40 | 6.29 | 2.14 |
| Median household income | ||||||||
| 0–25th | 827,281 | 16.4 | 11.4 | 0.59 | 0.57 | 0.36 | 6.56 | 2.52 |
| 26th–50th | 718,694 | 17.7 | 13.7 | 1.00 | 0.48 | 0.46 | 6.53 | 2.14 |
| 51st–75th | 617,952 | 18.3 | 14.5 | 0.06 | 0.77 | 0.40 | 6.12 | 2.02 |
| 76th–100th | 207,852 | 20.0 | 15.2 | 4.3e-5 | 1.37 | 5.26 | 7.59 | 2.22 |
| Urbanicity | ||||||||
| Large city | 1,497,608 | 13.9 | 12.1 | 0.01 | 0.90 | 0.45 | 5.97 | 2.22 |
| Small city | 719,150 | 20.5 | 14.3 | 0.02 | 0.85 | 0.47 | 12.06 | 2.55 |
| Micropolitan | 109,831 | 34.2 | 20.2 | 3.7e-3 | 1.12 | 0.40 | 14.53 | 3.20 |
| Rural | 50,154 | 50.9 | 28.0 | 0.02 | 0.83 | 0.73 | 11.20 | 1.82 |
| Calendar season | ||||||||
| Jan–Mar | 608,851 | 17.5 | 13.3 | 0.10 | 0.61 | 0.38 | 5.96 | 2.01 |
| Apr–Jun | 583,737 | 17.7 | 13.3 | 0.08 | 0.63 | 0.39 | 6.01 | 2.01 |
| Jul–Sep | 588,641 | 17.7 | 13.3 | 0.06 | 0.65 | 0.40 | 6.08 | 2.02 |
| Oct–Dec | 595,514 | 17.7 | 13.3 | 0.07 | 0.64 | 0.39 | 6.15 | 2.03 |
aT_all, average travel time in minutes for all patients; bT_60, average travel time in minutes for patients traveling ≤ 60 min