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Event (probability theory)

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152: 754: 36: 484:) to which a probability is assigned. A single outcome may be an element of many different events, and different events in an experiment are usually not equally likely, since they may include very different groups of outcomes. An event consisting of only a single outcome is called an 1037: 1106:
of subsets of the sample space. Under this definition, any subset of the sample space that is not an element of the 𝜎-algebra is not an event, and does not have a probability. With a reasonable specification of the probability space, however, all
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with no jokers, and draw a single card from the deck, then the sample space is a 52-element set, as each card is a possible outcome. An event, however, is any subset of the sample space, including any
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Defining all subsets of the sample space as events works well when there are only finitely many outcomes, but gives rise to problems when the sample space is infinite. For many standard
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Dekking, Frederik Michel; Kraaikamp, Cornelis; Lopuhaä, Hendrik Paul; Ludolf Erwin, Meester (2005). Dekking, Michel (ed.).
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of the sample space are defined as events). However, this approach does not work well in cases where the sample space is
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Since all events are sets, they are usually written as sets (for example, {1, 2, 3}), and represented graphically using
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it is possible, and often necessary, to exclude certain subsets of the sample space from being events (see
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of the sample space that contain multiple elements. So, for example, potential events include:
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In statistics and probability theory, set of outcomes to which a probability is assigned
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set derived from unions and intersections of intervals. However, the larger class of
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is finite, any subset of the sample space is an event (that is, all elements of the
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A modern introduction to probability and statistics: understanding why and how
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Algebra and trigonometry: Functions and Applications, Teacher's edition
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Probability, statistics and random processes for electrical engineering
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This rule can readily be applied to each of the example events above.
477: 1055:, the sample space is the set of real numbers or some subset of the 828:"Red and black at the same time without being a joker" (0 elements), 1242:{\displaystyle \{\omega \in \Omega \mid u<X(\omega )\leq v\}\,} 1574: – Set of random variables of which any two are independent 1687:. Springer texts in statistics. London : Springer. p. 14. 498:. An event that has more than one possible outcome is called a 29: 1166:
is a real-valued random variable defined on the sample space
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they are often written as predicates or indicators involving
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Pages displaying short descriptions of redirect targets
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of an experiment (that is, it is the probability that
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Pages displaying wikidata descriptions as a fallback
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Even though events are subsets of some sample space
60:. Unsourced material may be challenged and removed. 1519: 1475: 1418: 1391: 1356: 1277: 1241: 1181: 1158: 1134: 1031: 886: 866: 815: 793: 773: 678: 652: 632: 612: 588: 558: 538: 514: 1568: – Possible result of an experiment or trial 718: 1296: 975: 803:By the ratio of their areas, the probability of 1550: – An event that contains only one outcome 1357:{\displaystyle \Pr(u<X\leq v)=F(v)-F(u)\,.} 1652:(Classics ed.). Upper Saddle River, NJ: 1249:can be written more conveniently as, simply, 437: 8: 1285:This is especially common in formulas for a 1235: 1196: 843:"A Face card or a red suit" (32 elements), 690:, namely the complementary set (the event 444: 430: 131: 1488: 1443: 1431: 1411: 1372: 1350: 1294: 1271: 1254: 1238: 1194: 1171: 1151: 1124: 1016: 1008: 1001: 993: 990: 967: 958: 950: 942: 935: 927: 924: 907: 905: 879: 859: 808: 786: 766: 665: 645: 625: 605: 596:). The probability (with respect to some 575: 551: 531: 507: 120:Learn how and when to remove this message 1476:{\displaystyle \omega \in X^{-1}((u,v])} 752: 694:occurring), and together these define a 1584: 1544: – Opposite of a probability event 142: 1520:{\displaystyle u<X(\omega )\leq v.} 1091:sets proves more useful in practice. 7: 1075:, to work, it is necessary to use a 58:adding citations to reliable sources 1598:. Upper Saddle River, NJ: Pearson. 719:§ Events in probability spaces 1625:. Dover Publications. p. 18. 1205: 1173: 1126: 1013: 947: 908: 25: 1111:are elements of the 𝜎-algebra. 150: 34: 1775:Experiment (probability theory) 1278:{\displaystyle u<X\leq v\,.} 620:occurs is the probability that 69:"Event" probability theory 45:needs additional citations for 1622:Concepts of probability theory 1505: 1499: 1470: 1467: 1455: 1452: 1347: 1341: 1332: 1326: 1317: 1299: 1226: 1220: 1017: 1009: 1002: 994: 984: 978: 951: 943: 936: 928: 918: 912: 831:"The 5 of Hearts" (1 element), 698:: did the event occur or not? 217:Collectively exhaustive events 1: 1592:Leon-Garcia, Alberto (2008). 1063:sets, such as those that are 1708:Širjaev, Alʹbert N. (2016). 1392:{\displaystyle u<X\leq v} 1043:Events in probability spaces 837:"A Face card" (12 elements), 729:If we assemble a deck of 52 1743:Encyclopedia of Mathematics 1572:Pairwise independent events 1791: 1646:Foerster, Paul A. (2006). 1619:Pfeiffer, Paul E. (1978). 1073:conditional probabilities 1049:probability distributions 1182:{\displaystyle \Omega ,} 1135:{\displaystyle \Omega ,} 840:"A Spade" (13 elements), 781:is the sample space and 570:(or trial) (that is, if 387:Law of total probability 382:Conditional independence 271:Exponential distribution 256:Probability distribution 846:"A card" (52 elements). 686:). An event defines a 366:Conditional probability 1521: 1477: 1420: 1393: 1358: 1279: 1243: 1183: 1160: 1136: 1033: 888: 868: 834:"A King" (4 elements), 824: 817: 795: 775: 713:. So, when defining a 680: 679:{\displaystyle x\in S} 654: 634: 614: 590: 589:{\displaystyle x\in S} 560: 540: 516: 308:Continuous or discrete 261:Bernoulli distribution 1566:Outcome (probability) 1536:Atom (measure theory) 1522: 1478: 1421: 1394: 1359: 1280: 1244: 1184: 1161: 1137: 1034: 889: 869: 823:is approximately 0.4. 818: 796: 776: 756: 681: 655: 640:contains the outcome 635: 615: 591: 561: 546:contains the outcome 541: 517: 266:Binomial distribution 1487: 1430: 1410: 1399:is an example of an 1371: 1293: 1253: 1193: 1170: 1150: 1123: 904: 878: 858: 807: 785: 765: 711:uncountably infinite 701:Typically, when the 664: 644: 624: 604: 574: 550: 530: 506: 392:Law of large numbers 361:Marginal probability 286:Poisson distribution 135:Part of a series on 54:improve this article 1542:Complementary event 1089:Lebesgue measurable 1053:normal distribution 688:complementary event 598:probability measure 494:; that is, it is a 351:Complementary event 293:Probability measure 281:Pareto distribution 276:Normal distribution 1517: 1473: 1416: 1389: 1354: 1275: 1239: 1179: 1156: 1146:. For example, if 1132: 1115:A note on notation 1109:events of interest 1100:probability spaces 1029: 884: 864: 825: 813: 791: 771: 676: 650: 630: 610: 586: 556: 536: 512: 458:probability theory 402:Boole's inequality 338:Stochastic process 227:Mutual exclusivity 144:Probability theory 1755:Formal definition 1719:978-0-387-72205-4 1694:978-1-85233-896-1 1632:978-0-486-63677-1 1557:Independent event 1419:{\displaystyle X} 1159:{\displaystyle X} 1096:measure-theoretic 1022: 974: 970: 961: 956: 894:is the following 887:{\displaystyle A} 867:{\displaystyle P} 816:{\displaystyle A} 794:{\displaystyle A} 774:{\displaystyle B} 715:probability space 653:{\displaystyle x} 633:{\displaystyle S} 613:{\displaystyle S} 559:{\displaystyle x} 539:{\displaystyle S} 515:{\displaystyle S} 454: 453: 356:Joint probability 303:Bernoulli process 202:Probability space 130: 129: 122: 104: 16:(Redirected from 1782: 1751: 1724: 1723: 1705: 1699: 1698: 1678: 1672: 1671: 1643: 1637: 1636: 1616: 1610: 1609: 1589: 1562: 1553: 1548:Elementary event 1526: 1524: 1523: 1518: 1482: 1480: 1479: 1474: 1451: 1450: 1425: 1423: 1422: 1417: 1398: 1396: 1395: 1390: 1363: 1361: 1360: 1355: 1284: 1282: 1281: 1276: 1248: 1246: 1245: 1240: 1188: 1186: 1185: 1180: 1165: 1163: 1162: 1157: 1144:random variables 1141: 1139: 1138: 1133: 1085:Borel measurable 1038: 1036: 1035: 1030: 1028: 1024: 1023: 1021: 1020: 1012: 1006: 1005: 997: 991: 972: 971: 968: 959: 957: 955: 954: 946: 940: 939: 931: 925: 911: 899: 898: 893: 891: 890: 885: 873: 871: 870: 865: 822: 820: 819: 814: 800: 798: 797: 792: 780: 778: 777: 772: 740:elementary event 725:A simple example 685: 683: 682: 677: 659: 657: 656: 651: 639: 637: 636: 631: 619: 617: 616: 611: 600:) that an event 595: 593: 592: 587: 565: 563: 562: 557: 545: 543: 542: 537: 521: 519: 518: 513: 487:elementary event 446: 439: 432: 222:Elementary event 154: 132: 125: 118: 114: 111: 105: 103: 62: 38: 30: 21: 1790: 1789: 1785: 1784: 1783: 1781: 1780: 1779: 1765: 1764: 1736: 1733: 1728: 1727: 1720: 1707: 1706: 1702: 1695: 1680: 1679: 1675: 1668: 1645: 1644: 1640: 1633: 1618: 1617: 1613: 1606: 1591: 1590: 1586: 1581: 1560: 1551: 1532: 1485: 1484: 1483:if and only if 1439: 1428: 1427: 1408: 1407: 1369: 1368: 1291: 1290: 1251: 1250: 1191: 1190: 1168: 1167: 1148: 1147: 1121: 1120: 1117: 1098:description of 1094:In the general 1061:'badly behaved' 1045: 1007: 992: 966: 962: 941: 926: 902: 901: 896: 895: 876: 875: 856: 855: 805: 804: 802: 783: 782: 763: 762: 727: 696:Bernoulli trial 662: 661: 642: 641: 622: 621: 602: 601: 572: 571: 548: 547: 528: 527: 504: 503: 500:compound event. 450: 298:Random variable 249:Bernoulli trial 126: 115: 109: 106: 63: 61: 51: 39: 28: 23: 22: 15: 12: 11: 5: 1788: 1786: 1778: 1777: 1767: 1766: 1763: 1762: 1752: 1738:"Random event" 1732: 1731:External links 1729: 1726: 1725: 1718: 1700: 1693: 1673: 1666: 1638: 1631: 1611: 1604: 1583: 1582: 1580: 1577: 1576: 1575: 1569: 1563: 1554: 1545: 1539: 1531: 1528: 1516: 1513: 1510: 1507: 1504: 1501: 1498: 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325: 320: 315: 313:Expected value 310: 305: 295: 290: 289: 288: 283: 278: 273: 268: 263: 253: 252: 251: 241: 240: 239: 234: 229: 224: 219: 209: 204: 196: 195: 194: 193: 188: 183: 182: 181: 171: 170: 169: 156: 155: 147: 146: 140: 139: 128: 127: 42: 40: 33: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 1787: 1776: 1773: 1772: 1770: 1760: 1756: 1753: 1749: 1745: 1744: 1739: 1735: 1734: 1730: 1721: 1715: 1711: 1710:Probability-1 1704: 1701: 1696: 1690: 1686: 1685: 1677: 1674: 1669: 1667:0-13-165711-9 1663: 1659: 1655: 1654:Prentice Hall 1651: 1650: 1642: 1639: 1634: 1628: 1624: 1623: 1615: 1612: 1607: 1605:9780131471221 1601: 1597: 1596: 1588: 1585: 1578: 1573: 1570: 1567: 1564: 1558: 1555: 1549: 1546: 1543: 1540: 1537: 1534: 1533: 1529: 1527: 1514: 1511: 1508: 1502: 1496: 1493: 1490: 1464: 1461: 1458: 1447: 1444: 1440: 1436: 1433: 1413: 1406: 1402: 1401:inverse image 1386: 1383: 1380: 1377: 1374: 1367: 1351: 1344: 1338: 1335: 1329: 1323: 1320: 1314: 1311: 1308: 1305: 1302: 1288: 1272: 1268: 1265: 1262: 1259: 1256: 1232: 1229: 1223: 1217: 1214: 1211: 1208: 1202: 1199: 1176: 1153: 1145: 1129: 1114: 1112: 1108: 1105: 1101: 1097: 1092: 1090: 1086: 1082: 1078: 1074: 1070: 1066: 1065:nonmeasurable 1062: 1058: 1054: 1050: 1042: 1040: 1025: 998: 987: 981: 963: 932: 921: 915: 881: 861: 853: 852:Venn diagrams 845: 842: 839: 836: 833: 830: 827: 826: 810: 788: 768: 761:of an event. 760: 759:Euler diagram 755: 751: 749: 745: 741: 737: 736:singleton set 732: 731:playing cards 724: 722: 720: 716: 712: 708: 704: 699: 697: 691: 689: 673: 670: 667: 647: 627: 607: 599: 583: 580: 577: 569: 553: 533: 523: 509: 501: 497: 496:singleton set 491: 488: 485: 483: 479: 475: 471: 467: 463: 459: 447: 442: 440: 435: 433: 428: 427: 425: 424: 419: 416: 414: 411: 410: 409: 408: 403: 400: 398: 395: 393: 390: 388: 385: 383: 380: 378: 375: 374: 373: 372: 367: 364: 362: 359: 357: 354: 352: 349: 348: 347: 346: 339: 336: 334: 331: 329: 326: 324: 321: 319: 316: 314: 311: 309: 306: 304: 301: 300: 299: 296: 294: 291: 287: 284: 282: 279: 277: 274: 272: 269: 267: 264: 262: 259: 258: 257: 254: 250: 247: 246: 245: 242: 238: 235: 233: 230: 228: 225: 223: 220: 218: 215: 214: 213: 210: 208: 205: 203: 200: 199: 198: 197: 192: 189: 187: 186:Indeterminism 184: 180: 177: 176: 175: 172: 168: 165: 164: 163: 160: 159: 158: 157: 153: 149: 148: 145: 141: 138: 134: 133: 124: 121: 113: 102: 99: 95: 92: 88: 85: 81: 78: 74: 71: –  70: 66: 65:Find sources: 59: 55: 49: 48: 43:This article 41: 37: 32: 31: 19: 1759:Mizar system 1741: 1709: 1703: 1683: 1676: 1648: 1641: 1621: 1614: 1594: 1587: 1118: 1093: 1057:real numbers 1046: 874:of an event 849: 801:is an event. 728: 703:sample space 700: 499: 492:atomic event 482:sample space 461: 455: 418:Tree diagram 413:Venn diagram 377:Independence 323:Markov chain 211: 207:Sample space 116: 110:January 2018 107: 97: 90: 83: 76: 64: 52:Please help 47:verification 44: 18:Random event 1287:probability 522:is said to 333:Random walk 174:Determinism 162:Probability 1656:. p.  1403:under the 1289:, such as 1189:the event 1104:𝜎-algebra 721:, below). 568:experiment 474:experiment 244:Experiment 191:Randomness 137:statistics 80:newspapers 1748:EMS Press 1509:≤ 1503:ω 1445:− 1437:∈ 1434:ω 1384:≤ 1336:− 1312:≤ 1266:≤ 1230:≤ 1224:ω 1209:∣ 1206:Ω 1203:∈ 1200:ω 1174:Ω 1127:Ω 1014:Ω 948:Ω 744:empty set 707:power set 671:∈ 581:∈ 502:An event 237:Singleton 1769:Category 1530:See also 1426:because 470:outcomes 318:Variance 1757:in the 1750:, 2001 1405:mapping 1083:is the 897:formula 742:), the 566:of the 480:of the 232:Outcome 94:scholar 1716:  1691:  1664:  1629:  1602:  973:  960:  490:or an 478:subset 472:of an 179:System 167:Axioms 96:  89:  82:  75:  67:  1579:Notes 1069:joint 524:occur 464:is a 462:event 460:, an 212:Event 101:JSTOR 87:books 1714:ISBN 1689:ISBN 1662:ISBN 1627:ISBN 1600:ISBN 1494:< 1378:< 1364:The 1306:< 1260:< 1215:< 1071:and 738:(an 73:news 1658:634 1366:set 757:An 692:not 526:if 476:(a 468:of 466:set 456:In 56:by 1771:: 1746:, 1740:, 1660:. 1297:Pr 976:Pr 900:: 1761:. 1722:. 1697:. 1670:. 1635:. 1608:. 1515:. 1512:v 1506:) 1500:( 1497:X 1491:u 1471:) 1468:] 1465:v 1462:, 1459:u 1456:( 1453:( 1448:1 1441:X 1414:X 1387:v 1381:X 1375:u 1352:. 1348:) 1345:u 1342:( 1339:F 1333:) 1330:v 1327:( 1324:F 1321:= 1318:) 1315:v 1309:X 1303:u 1300:( 1273:. 1269:v 1263:X 1257:u 1236:} 1233:v 1227:) 1221:( 1218:X 1212:u 1197:{ 1177:, 1154:X 1130:, 1026:) 1018:| 1010:| 1003:| 999:A 995:| 988:= 985:) 982:A 979:( 964:( 952:| 944:| 937:| 933:A 929:| 922:= 919:) 916:A 913:( 909:P 882:A 862:P 811:A 789:A 769:B 674:S 668:x 648:x 628:S 608:S 584:S 578:x 554:x 534:S 510:S 445:e 438:t 431:v 123:) 117:( 112:) 108:( 98:· 91:· 84:· 77:· 50:. 20:)

Index

Random event

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"Event" probability theory
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statistics
Probability theory

Probability
Axioms
Determinism
System
Indeterminism
Randomness
Probability space
Sample space
Event
Collectively exhaustive events
Elementary event
Mutual exclusivity
Outcome
Singleton
Experiment

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