Journal of Advanced Transportation

Research Article

Distribution-Free Model for Ambulance Location Problem with Ambiguous Demand

Table 6

Computational results on instances with data generated from normal distribution.
Sampling approachMIP-DF1MIP-DF2Sampling approachMIP-DF1MIP-DF2Sampling approachMIP-DF1MIP-DF2
CTObjSel (%)Sel (%)Sel (%)CTObjSel (%)Sel (%)Sel (%)CTObjSel (%)Sel (%)Sel (%)
1 (2,6) 2.7 90 72.94 99.64 91.17 2.7 94 78.44 99.70 92.02 2.558 106 84.22 100.00 92.08
2 (4,12) 4.6 170 79.61 99.21 92.83 4.8 183 83.28 99.82 92.83 4.508 183 88.23 100.00 93.70
3 (6,18) 6.8 258 75.78 99.16 92.28 6.8 280 77.98 99.71 94.17 6.803 307 76.58 99.98 94.47
4 (8,24) 9.3 315 80.00 98.99 93.67 9.6 337 83.79 99.79 94.67 9.373 368 84.38 99.99 95.79
5 (10,30) 12.0 413 78.41 99.27 94.37 12.4 443 87.63 99.63 94.76 12.62 499 88.50 99.98 97.08
6 (12,36) 15.5 476 79.21 99.19 95.19 16.2 504 81.24 99.82 95.82 16.021 536 89.54 100.00 97.56
7 (14,42) 19.5 573 79.76 99.33 95.98 19.6 609 82.87 99.75 96.19 20.11 646 84.67 99.99 97.67
8 (16,48) 23.2 687 80.31 99.18 97.05 23.5 727 81.15 99.65 96.50 24.04 772 82.78 99.99 97.65
9 (18,54) 29.3 692 80.86 98.98 97.59 29.1 734 84.64 99.74 97.55 29.815 796 86.17 99.98 98.35
10 (20,60) 35.6 796 79.84 99.37 97.70 35.8 842 82.23 99.88 97.65 37.973 921 88.46 100.00 98.38
11 (22,66) 42.1 829 81.01 99.40 97.55 43.6 877 82.11 99.86 97.86 45.148 959 84.97 99.99 97.89
12 (24,72) 51.4 1023 80.33 99.51 97.85 50.1 1085 81.62 99.83 97.88 52.073 1147 83.21 99.99 98.24
13 (26,78) 59.2 1023 81.38 99.16 98.85 59.9 1087 84.11 99.70 98.45 62.937 1194 86.09 99.98 97.95
14 (28,84) 72.8 1099 82.35 99.13 99.15 72.2 1168 84.35 99.87 98.06 75.053 1270 85.67 99.97 98.34
15 (30,90) 85.5 1089 81.87 99.22 98.61 88.0 1157 83.76 99.76 97.96 89.222 1300 86.11 99.96 97.98
16 (32,96) 100.9 1158 87.70 98.97 97.88 96.6 1231 88.45 99.84 98.23 106.288 1359 89.97 99.99 98.48
17 (34,102) 115.4 1299 84.34 99.25 98.49 113.7 1377 86.01 99.80 97.98 123.869 1493 87.98 99.96 98.77
18 (36,108) 140.7 1411 83.21 99.27 98.66 133.9 1495 83.01 99.65 98.22 133.807 1601 85.67 99.99 98.34
19 (38,114) 170.2 1506 82.06 99.15 98.05 167.2 1598 89.77 99.78 98.45 152.999 1694 89.98 99.99 98.47
20 (40,120) 209.1 1635 85.28 99.18 98.89 191.6 1737 88.05 99.76 98.37 189.002 1833 90.12 99.99 97.91
21 (42,126) 284.3 1622 85.50 99.34 99.13 243.2 1718 88.86 99.74 98.13 239.913 1815 90.08 100.00 98.15
22 (44,132) 330.0 1736 84.49 99.40 98.59 279.5 1843 87.86 99.77 97.56 253.106 1948 89.97 99.99 98.26
23 (46,138) 374.1 1934 81.33 99.11 98.76 314.3 2050 88.76 99.81 97.85 274.583 2173 90.14 99.99 98.58
24 (48,144) 453.1 1961 82.45 99.09 98.46 351.5 2090 83.44 99.93 98.19 308.089 2211 86.61 99.99 98.83
25 (50,150) 471.5 1924 81.11 99.29 98.88 395.9 2041 82.79 99.96 98.37 351.093 2158 85.27 99.99 98.27
26 (52,156) 522.3 1911 80.96 98.98 98.57 430.1 2025 82.51 99.97 97.57 421.747 2146 84.97 99.99 99.14
27 (54,162) 599.4 2095 83.87 99.08 97.75 483.5 2226 84.97 99.74 97.80 461.443 2359 86.95 99.99 98.37
28 (56,168) 640.6 2111 84.11 99.06 97.98 533.6 2240 85.58 99.91 98.20 494.113 2371 92.49 99.99 98.16
29 (58,174) 689.7 2176 80.12 99.16 97.91 594.8 2311 82.11 99.84 97.65 624.835 2445 85.31 100.00 98.51
30 (60,180) 743.6 2391 81.11 99.13 97.66 655.8 2533 83.05 99.68 97.95 696.116 2682 85.75 99.99 97.99
31 (62,186) 811.8 2282 81.19 99.28 98.06 706.9 2422 84.17 99.73 98.73 797.768 2564 86.67 99.99 98.46
32 (64,192) 889.5 2519 82.23 99.19 97.57 785.7 2675 86.31 99.82 97.69 864.813 2827 89.76 100.00 99.05
33 (66,198) 1123.5 2533 85.63 99.28 98.11 916.2 2688 85.47 99.79 98.28 973.089 2843 86.57 99.99 98.46
34 (68,204) 1158.7 2534 82.49 99.26 98.47 954.9 2686 87.98 99.38 98.56 1052.3 3041 89.99 100.00 98.77
35 (70,210) 1164.9 2715 80.98 98.95 98.72 1034.5 2880 86.02 99.98 98.69 1127.2 3052 90.21 99.99 98.97
36 (72,216) 1222.4 2825 84.03 99.58 97.70 1116.5 3002 86.57 99.99 98.39 1245.6 3175 91.13 99.99 98.64
37 (74,222) 1297.8 2830 83.57 99.37 97.95 1185.0 3005 84.96 99.98 98.94 1345.8 3176 88.27 99.99 99.05
38 (76,228) 1342.6 2844 82.67 99.66 97.59 1279.5 3019 86.04 99.99 97.97 1515.5 3121 89.78 99.99 98.53
39 (78,234) 1500.3 2955 83.03 99.56 98.67 1381.6 3132 85.88 99.96 98.85 1504.1 3310 90.16 99.99 99.12
40 (80,240) 1649.5 2978 82.57 99.54 98.26 1489.6 3160 84.95 99.97 98.37 1656.3 3349 89.57 99.99 99.33
Average461.9 1585.5 81.74 99.25 97.42 407.7 1682.8 84.57 99.81 97.43 435.0 1793.8 87.32 99.99 97.94