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Elementary effects method

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38:-based measures is not affordable. Like all screening, the EE method provides qualitative sensitivity analysis measures, i.e. measures which allow the identification of non-influential inputs or which allow to rank the input factors in order of importance, but do not quantify exactly the relative importance of the inputs. 1543: 636: 1861:
Iooss, Bertrand, and Paul Lemaître. 2015. “A Review on Global Sensitivity Analysis Methods.” In Uncertainty Management in Simulation-Optimization of Complex Systems, edited by G. Dellino and C. Meloni, 101–22. Boston, MA: Springer, Boston, MA.
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An efficient technical scheme to construct the trajectories used in the EE method is presented in the original paper by Morris while an improvement strategy aimed at better exploring the input space is proposed by Campolongo et al..
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These two measures need to be read together (e.g. on a two-dimensional graph) in order to rank input factors in order of importance and identify those inputs which do not influence the output variability. Low values of both
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In case input factors are not uniformly distributed, the best practice is to sample in the space of the quantiles and to obtain the inputs values using inverse cumulative distribution functions. Note that in this case
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Wei, Pengfei, Zhenzhou Lu, and Jingwen Song. 2015. “Variable Importance Analysis: A Comprehensive Review.” Reliability Engineering & System Safety 142: 399–432.
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Borgonovo, Emanuele, and Elmar Plischke. 2016. “Sensitivity Analysis: A Review of Recent Advances.” European Journal of Operational Research 248 (3): 869–87.
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Norton, J.P. 2015. “An Introduction to Sensitivity Assessment of Simulation Models.” Environmental Modelling & Software 69 (C): 166–74.
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in the space of the inputs, where inputs are randomly moved One-At-a-Time (OAT). In this design, each model input is assumed to vary across
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Campolongo, F., J. Cariboni, and A. Saltelli (2007). An effective screening design for sensitivity analysis of large models.
1620:, which on its own is sufficient to provide a reliable ranking of the input factors. The revised measure is the mean of the 34:
or for a model with a large number of inputs, where the costs of estimating other sensitivity analysis measures such as the
1930: 1538:{\displaystyle \sigma _{i}={\sqrt {{\frac {1}{(r-1)}}\sum _{j=1}^{r}\left(d_{i}\left(X^{(j)}\right)-\mu _{i}\right)^{2}}}} 645: 631:{\displaystyle d_{i}(X)={\frac {Y(X_{1},\ldots ,X_{i-1},X_{i}+\Delta ,X_{i+1},\ldots ,X_{k})-Y(\mathbf {X} )}{\Delta }}} 977: 1621: 369: 92: 1817: 944:{\displaystyle d_{i}\left(X^{(1)}\right),d_{i}\left(X^{(2)}\right),\ldots ,d_{i}\left(X^{(r)}\right)} 24: 761: 1770: 1298: 1075: 31: 1731:{\displaystyle \mu _{i}^{*}={\frac {1}{r}}\sum _{j=1}^{r}\left|d_{i}\left(X^{(j)}\right)\right|} 1593:
An improvement of this method was developed by Campolongo et al. who proposed a revised measure
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The original EE method of Morris provides two sensitivity measures for each input factor:
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Morris, M. D. (1991). Factorial sampling plans for preliminary computational experiments.
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These two measures are obtained through a design based on the construction of a series of
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solves the problem of the effects of opposite signs which occurs when the model is non-
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selected levels in the space of the input factors. The region of experimentation
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To exemplify the EE method, let us assume to consider a mathematical model with
1393:{\displaystyle \mu _{i}={\frac {1}{r}}\sum _{j=1}^{r}d_{i}\left(X^{(j)}\right)} 1863: 228: 30:
EE is applied to identify non-influential inputs for a computationally costly
1889: 1849: 1099: 196:, assessing the overall importance of an input factor on the model output; 35: 1773:
and which can cancel each other out, thus resulting in a low value for
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of the absolute values of the elementary effects of the input factors:
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equals the step taken by the inputs in the space of the quantiles.
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of the distribution of the elementary effects of each input:
1074:~ 4-10, depending on the number of input factors, on the 1078:
of the model and on the choice of the number of levels
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points since input factors move one by one of a step
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be the output of interest (a scalar for simplicity):
72: 52: 711:{\displaystyle \mathbf {X} =(X_{1},X_{2},...X_{k})} 1785: 1761: 1730: 1612: 1582: 1562: 1537: 1392: 1289: 1269: 1246: 1222: 1173: 1153: 1133: 1113: 1090: 1066: 1043: 966: 943: 812: 791: 750: 730: 710: 630: 454: 358: 338: 303: 283: 263: 243: 211: 188: 161: 78: 58: 820:elementary effects are estimated for each input 1044:{\displaystyle X^{(1)},X^{(2)},\ldots ,X^{(r)}} 1814:https://www.stat.iastate.edu/people/max-morris 1877:https://doi.org/10.1016/j.envsoft.2015.03.020 23:is one of the most used screening methods in 8: 738:such that the transformed point is still in 449: 373: 1864:https://doi.org/10.1007/978-1-4899-7547-8_5 455:{\displaystyle \{0,1/(p-1),2/(p-1),...,1\}} 1890:https://doi.org/10.1016/j.ress.2015.05.018 1850:https://doi.org/10.1016/J.EJOR.2015.06.032 162:{\displaystyle Y=f(X_{1},X_{2},...X_{k}).} 1778: 1753: 1747: 1707: 1693: 1678: 1667: 1653: 1644: 1639: 1633: 1604: 1598: 1575: 1555: 1527: 1516: 1493: 1479: 1463: 1452: 1424: 1422: 1413: 1407: 1374: 1360: 1350: 1339: 1325: 1316: 1310: 1282: 1262: 1239: 1191: 1186: 1166: 1146: 1126: 1106: 1083: 1059: 1029: 1004: 985: 979: 959: 925: 911: 882: 868: 845: 831: 825: 805: 763: 743: 723: 699: 677: 664: 649: 647: 614: 596: 571: 552: 533: 514: 501: 483: 477: 411: 385: 371: 351: 319: 296: 276: 256: 236: 204: 181: 147: 125: 112: 94: 71: 51: 1827: 1825: 1806: 469:for each input factor is defined as: 7: 1903:Environmental Modelling and Software 1590:correspond to a non-influent input. 465:Along each trajectory the so-called 19:Published in 1991 by Max Morris the 462:while all the others remain fixed. 1241: 1168: 1128: 745: 725: 623: 561: 353: 258: 14: 1297:are defined as the mean and the 650: 615: 314:Each trajectory is composed of 1816:Home Page of Max D. Morris at 1714: 1708: 1500: 1494: 1442: 1430: 1381: 1375: 1217: 1214: 1202: 1196: 1036: 1030: 1011: 1005: 992: 986: 932: 926: 889: 883: 852: 846: 792:{\displaystyle i=1,\ldots ,k.} 705: 657: 619: 611: 602: 507: 495: 489: 428: 416: 402: 390: 333: 321: 153: 105: 21:elementary effects (EE) method 1: 1947: 718:is any selected value in 223:effects and interactions. 1762:{\displaystyle \mu ^{*}} 1613:{\displaystyle \mu ^{*}} 1583:{\displaystyle \sigma } 1290:{\displaystyle \sigma } 1247:{\displaystyle \Delta } 1174:{\displaystyle \Delta } 1134:{\displaystyle \Delta } 751:{\displaystyle \Omega } 731:{\displaystyle \Omega } 359:{\displaystyle \Delta } 264:{\displaystyle \Omega } 212:{\displaystyle \sigma } 1787: 1763: 1732: 1683: 1614: 1584: 1564: 1539: 1468: 1394: 1355: 1291: 1271: 1248: 1224: 1175: 1155: 1135: 1115: 1092: 1068: 1045: 968: 945: 814: 793: 752: 732: 712: 632: 456: 360: 340: 305: 285: 265: 245: 213: 190: 163: 80: 60: 1926:Mathematical modeling 1818:Iowa State University 1788: 1764: 1733: 1663: 1615: 1585: 1565: 1540: 1448: 1395: 1335: 1292: 1272: 1249: 1225: 1176: 1156: 1136: 1116: 1093: 1069: 1046: 969: 946: 815: 794: 753: 733: 713: 633: 457: 361: 341: 339:{\displaystyle (k+1)} 306: 286: 266: 246: 214: 191: 164: 81: 61: 1931:Sensitivity analysis 1786:{\displaystyle \mu } 1777: 1746: 1632: 1597: 1574: 1563:{\displaystyle \mu } 1554: 1406: 1309: 1281: 1270:{\displaystyle \mu } 1261: 1238: 1185: 1165: 1145: 1125: 1105: 1082: 1058: 978: 958: 824: 804: 762: 742: 722: 646: 476: 370: 350: 318: 295: 275: 255: 235: 203: 189:{\displaystyle \mu } 180: 93: 70: 50: 25:sensitivity analysis 1649: 66:input factors. Let 1909:, 1509–1518. 1783: 1759: 1728: 1635: 1610: 1580: 1560: 1535: 1390: 1299:standard deviation 1287: 1267: 1244: 1223:{\displaystyle p/} 1220: 1171: 1151: 1131: 1111: 1088: 1076:computational cost 1064: 1041: 964: 941: 810: 789: 748: 728: 708: 628: 452: 356: 336: 301: 281: 261: 241: 209: 186: 159: 76: 56: 32:mathematical model 1661: 1533: 1446: 1333: 1257:The two measures 1154:{\displaystyle p} 1114:{\displaystyle p} 1091:{\displaystyle p} 1067:{\displaystyle r} 967:{\displaystyle r} 953:randomly sampling 813:{\displaystyle r} 626: 467:elementary effect 304:{\displaystyle p} 284:{\displaystyle k} 244:{\displaystyle p} 79:{\displaystyle Y} 59:{\displaystyle k} 1938: 1910: 1899: 1893: 1886: 1880: 1873: 1867: 1859: 1853: 1846: 1840: 1829: 1820: 1811: 1792: 1790: 1789: 1784: 1768: 1766: 1765: 1760: 1758: 1757: 1737: 1735: 1734: 1729: 1727: 1723: 1722: 1718: 1717: 1698: 1697: 1682: 1677: 1662: 1654: 1648: 1643: 1619: 1617: 1616: 1611: 1609: 1608: 1589: 1587: 1586: 1581: 1569: 1567: 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287: 282: 270: 268: 267: 262: 250: 248: 247: 242: 218: 216: 215: 210: 195: 193: 192: 187: 168: 166: 165: 160: 152: 151: 130: 129: 117: 116: 85: 83: 82: 77: 65: 63: 62: 57: 16:Screening method 1946: 1945: 1941: 1940: 1939: 1937: 1936: 1935: 1916: 1915: 1914: 1913: 1900: 1896: 1887: 1883: 1874: 1870: 1860: 1856: 1847: 1843: 1830: 1823: 1812: 1808: 1803: 1775: 1774: 1749: 1744: 1743: 1703: 1699: 1689: 1688: 1684: 1630: 1629: 1625: 1600: 1595: 1594: 1572: 1571: 1552: 1551: 1512: 1489: 1485: 1475: 1474: 1470: 1469: 1429: 1409: 1404: 1403: 1370: 1366: 1356: 1312: 1307: 1306: 1302: 1279: 1278: 1259: 1258: 1236: 1235: 1183: 1182: 1163: 1162: 1143: 1142: 1123: 1122: 1103: 1102: 1080: 1079: 1056: 1055: 1025: 1000: 981: 976: 975: 956: 955: 921: 917: 907: 878: 874: 864: 841: 837: 827: 822: 821: 802: 801: 760: 759: 758:for each index 740: 739: 720: 719: 695: 673: 660: 644: 643: 592: 567: 548: 529: 510: 503: 479: 474: 473: 368: 367: 348: 347: 316: 315: 293: 292: 273: 272: 253: 252: 233: 232: 201: 200: 178: 177: 143: 121: 108: 91: 90: 68: 67: 48: 47: 44: 17: 12: 11: 5: 1944: 1942: 1934: 1933: 1928: 1918: 1917: 1912: 1911: 1894: 1881: 1868: 1854: 1841: 1821: 1805: 1804: 1802: 1799: 1782: 1756: 1752: 1740: 1739: 1726: 1721: 1716: 1713: 1710: 1706: 1702: 1696: 1692: 1687: 1681: 1676: 1673: 1670: 1666: 1660: 1657: 1652: 1647: 1642: 1638: 1607: 1603: 1579: 1559: 1547: 1546: 1530: 1525: 1519: 1515: 1511: 1507: 1502: 1499: 1496: 1492: 1488: 1482: 1478: 1473: 1466: 1461: 1458: 1455: 1451: 1444: 1441: 1438: 1435: 1432: 1428: 1421: 1416: 1412: 1401: 1388: 1383: 1380: 1377: 1373: 1369: 1363: 1359: 1353: 1348: 1345: 1342: 1338: 1332: 1329: 1324: 1319: 1315: 1286: 1266: 1243: 1219: 1216: 1213: 1210: 1207: 1204: 1201: 1198: 1194: 1190: 1170: 1150: 1130: 1110: 1087: 1063: 1038: 1035: 1032: 1028: 1024: 1021: 1018: 1013: 1010: 1007: 1003: 999: 994: 991: 988: 984: 963: 939: 934: 931: 928: 924: 920: 914: 910: 906: 903: 900: 896: 891: 888: 885: 881: 877: 871: 867: 863: 859: 854: 851: 848: 844: 840: 834: 830: 809: 788: 785: 782: 779: 776: 773: 770: 767: 747: 727: 707: 702: 698: 694: 691: 688: 685: 680: 676: 672: 667: 663: 659: 656: 652: 640: 639: 625: 621: 617: 613: 610: 607: 604: 599: 595: 591: 588: 585: 580: 577: 574: 570: 566: 563: 560: 555: 551: 547: 542: 539: 536: 532: 528: 525: 522: 517: 513: 509: 506: 500: 497: 494: 491: 486: 482: 451: 448: 445: 442: 439: 436: 433: 430: 427: 424: 421: 418: 414: 410: 407: 404: 401: 398: 395: 392: 388: 384: 381: 378: 375: 355: 335: 332: 329: 326: 323: 300: 280: 260: 240: 225: 224: 208: 197: 185: 170: 169: 158: 155: 150: 146: 142: 139: 136: 133: 128: 124: 120: 115: 111: 107: 104: 101: 98: 75: 55: 43: 40: 15: 13: 10: 9: 6: 4: 3: 2: 1943: 1932: 1929: 1927: 1924: 1923: 1921: 1908: 1904: 1898: 1895: 1891: 1885: 1882: 1878: 1872: 1869: 1865: 1858: 1855: 1851: 1845: 1842: 1838: 1834: 1833:Technometrics 1828: 1826: 1822: 1819: 1815: 1810: 1807: 1800: 1798: 1794: 1780: 1772: 1754: 1750: 1724: 1719: 1711: 1704: 1700: 1694: 1690: 1685: 1679: 1674: 1671: 1668: 1664: 1658: 1655: 1650: 1645: 1640: 1636: 1628: 1627: 1626: 1623: 1605: 1601: 1591: 1577: 1557: 1528: 1523: 1517: 1513: 1509: 1505: 1497: 1490: 1486: 1480: 1476: 1471: 1464: 1459: 1456: 1453: 1449: 1439: 1436: 1433: 1426: 1419: 1414: 1410: 1402: 1386: 1378: 1371: 1367: 1361: 1357: 1351: 1346: 1343: 1340: 1336: 1330: 1327: 1322: 1317: 1313: 1305: 1304: 1303: 1300: 1284: 1264: 1255: 1231: 1211: 1208: 1205: 1199: 1192: 1188: 1148: 1108: 1101: 1085: 1077: 1061: 1052: 1033: 1026: 1022: 1019: 1016: 1008: 1001: 997: 989: 982: 961: 954: 937: 929: 922: 918: 912: 908: 904: 901: 898: 894: 886: 879: 875: 869: 865: 861: 857: 849: 842: 838: 832: 828: 807: 799: 786: 783: 780: 777: 774: 771: 768: 765: 700: 696: 692: 689: 686: 683: 678: 674: 670: 665: 661: 654: 608: 605: 597: 593: 589: 586: 583: 578: 575: 572: 568: 564: 558: 553: 549: 545: 540: 537: 534: 530: 526: 523: 520: 515: 511: 504: 498: 492: 484: 480: 472: 471: 470: 468: 463: 446: 443: 440: 437: 434: 431: 425: 422: 419: 412: 408: 405: 399: 396: 393: 386: 382: 379: 376: 330: 327: 324: 312: 311:-level grid. 298: 291:-dimensional 278: 238: 230: 222: 219:, describing 206: 198: 183: 175: 174: 173: 156: 148: 144: 140: 137: 134: 131: 126: 122: 118: 113: 109: 102: 99: 96: 89: 88: 87: 73: 53: 41: 39: 37: 33: 28: 26: 22: 1906: 1902: 1897: 1884: 1871: 1857: 1844: 1836: 1832: 1809: 1795: 1741: 1622:distribution 1592: 1548: 1256: 1232: 1053: 800: 641: 466: 464: 313: 229:trajectories 226: 199:the measure 176:the measure 171: 45: 29: 20: 18: 1742:The use of 42:Methodology 1920:Categories 1839:, 161–174. 1801:References 1100:parameters 271:is thus a 221:non-linear 1781:μ 1771:monotonic 1755:∗ 1751:μ 1665:∑ 1646:∗ 1637:μ 1606:∗ 1602:μ 1578:σ 1558:μ 1514:μ 1510:− 1450:∑ 1437:− 1411:σ 1337:∑ 1314:μ 1285:σ 1265:μ 1242:Δ 1209:− 1181:equal to 1169:Δ 1161:even and 1129:Δ 1020:… 902:… 778:… 746:Ω 726:Ω 624:Δ 606:− 587:… 562:Δ 538:− 524:… 423:− 397:− 354:Δ 259:Ω 207:σ 184:μ 1054:Usually 36:variance 974:points 642:where 1570:and 1277:and 1121:and 1141:is 951:by 366:in 1922:: 1907:22 1905:, 1879:. 1866:. 1852:. 1837:33 1835:, 1824:^ 1793:. 1051:. 27:. 1892:. 1738:. 1725:| 1720:) 1715:) 1712:j 1709:( 1705:X 1701:( 1695:i 1691:d 1686:| 1680:r 1675:1 1672:= 1669:j 1659:r 1656:1 1651:= 1641:i 1545:. 1529:2 1524:) 1518:i 1506:) 1501:) 1498:j 1495:( 1491:X 1487:( 1481:i 1477:d 1472:( 1465:r 1460:1 1457:= 1454:j 1443:) 1440:1 1434:r 1431:( 1427:1 1420:= 1415:i 1400:, 1387:) 1382:) 1379:j 1376:( 1372:X 1368:( 1362:i 1358:d 1352:r 1347:1 1344:= 1341:j 1331:r 1328:1 1323:= 1318:i 1218:] 1215:) 1212:1 1206:p 1203:( 1200:2 1197:[ 1193:/ 1189:p 1149:p 1109:p 1086:p 1062:r 1037:) 1034:r 1031:( 1027:X 1023:, 1017:, 1012:) 1009:2 1006:( 1002:X 998:, 993:) 990:1 987:( 983:X 962:r 938:) 933:) 930:r 927:( 923:X 919:( 913:i 909:d 905:, 899:, 895:) 890:) 887:2 884:( 880:X 876:( 870:i 866:d 862:, 858:) 853:) 850:1 847:( 843:X 839:( 833:i 829:d 808:r 787:. 784:k 781:, 775:, 772:1 769:= 766:i 706:) 701:k 697:X 693:. 690:. 687:. 684:, 679:2 675:X 671:, 666:1 662:X 658:( 655:= 651:X 638:, 620:) 616:X 612:( 609:Y 603:) 598:k 594:X 590:, 584:, 579:1 576:+ 573:i 569:X 565:, 559:+ 554:i 550:X 546:, 541:1 535:i 531:X 527:, 521:, 516:1 512:X 508:( 505:Y 499:= 496:) 493:X 490:( 485:i 481:d 450:} 447:1 444:, 441:. 438:. 435:. 432:, 429:) 426:1 420:p 417:( 413:/ 409:2 406:, 403:) 400:1 394:p 391:( 387:/ 383:1 380:, 377:0 374:{ 334:) 331:1 328:+ 325:k 322:( 299:p 279:k 239:p 157:. 154:) 149:k 145:X 141:. 138:. 135:. 132:, 127:2 123:X 119:, 114:1 110:X 106:( 103:f 100:= 97:Y 74:Y 54:k

Index

sensitivity analysis
mathematical model
variance
non-linear
trajectories
randomly sampling
computational cost
parameters
standard deviation
distribution
monotonic
https://www.stat.iastate.edu/people/max-morris
Iowa State University


https://doi.org/10.1016/J.EJOR.2015.06.032
https://doi.org/10.1007/978-1-4899-7547-8_5
https://doi.org/10.1016/j.envsoft.2015.03.020
https://doi.org/10.1016/j.ress.2015.05.018
Categories
Mathematical modeling
Sensitivity analysis

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