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Conditional probability table

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With more than one conditioning variable, the table would still have one row for each potential value of the variable whose conditional probabilities are to be given, and there would be one column for each possible combination of values of the conditioning variables.
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Moreover, the number of columns in the table could be substantially expanded to display the probabilities of the variable of interest conditional on specific values of only some, rather than all, of the other variables.
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of a single variable with respect to the others (i.e., the probability of each possible value of one variable if we know the values taken on by the other variables). For example, assume there are three random variables
751: 311: 541: 651: 821: 189: 435: 598: 568: 462: 391: 364: 236: 39: 482: 333: 209: 86: 58: 65: 105: 1061: 72: 839: 43: 662: 54: 241: 127: 32: 487: 603: 134: 79: 780: 141: 921: 656: 396: 964:=1. Combining these pieces of information gives us this table of conditional probabilities for 774: 948:=0, which is 4/9 ÷ 6/9 = 4/6. Likewise, in the same column we find that the probability that 573: 956:=0 is 2/9 ÷ 6/9 = 2/6. In the same way, we can also find the conditional probabilities for 546: 440: 369: 342: 214: 828: 130: 467: 316: 194: 1055: 904:
Each of the four central cells shows the probability of a particular combination of
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equals any of the values it can have – that is, the column sum 6/9 is the
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the CPT for any one of them has the number of cells equal to the product
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form. As an example with only two variables, the values of
940:=0, we compute the fraction of the probabilities in the 746:{\displaystyle P(x_{1}=a_{k}\mid x_{2}=b_{j})=T_{kj},} 912:
values. The first column sum is the probability that
783: 665: 606: 576: 549: 490: 470: 443: 399: 372: 345: 319: 244: 217: 197: 144: 211:states. Then, the conditional probability table of 46:. Unsourced material may be challenged and removed. 815: 745: 645: 592: 562: 535: 476: 456: 429: 385: 358: 327: 305: 230: 203: 183: 655:A conditional probability table can be put into 393:and for each possible combination of values of 335:means “given the values of” – for each of the 306:{\displaystyle P(x_{1}=a_{k}\mid x_{2},x_{3})} 126:is defined for a set of discrete and mutually 1042:Machine learning: a probabilistic perspective 8: 928:=0. If we want to find the probability that 238:provides the conditional probability values 798: 788: 782: 731: 715: 702: 689: 676: 664: 634: 621: 611: 605: 581: 575: 554: 548: 536:{\displaystyle x_{1},x_{2},\ldots ,x_{M}} 527: 508: 495: 489: 469: 448: 442: 418: 413: 404: 398: 377: 371: 350: 344: 320: 318: 294: 281: 268: 255: 243: 222: 216: 196: 175: 162: 149: 143: 106:Learn how and when to remove this message 970: 844: 1032: 646:{\displaystyle K_{1}K_{2}\cdots K_{M}.} 7: 44:adding citations to reliable sources 124:conditional probability table (CPT) 14: 816:{\displaystyle \sum _{k}T_{kj}=1} 777:since the columns sum to 1; i.e. 184:{\displaystyle x_{1},x_{2},x_{3}} 827:. For example, suppose that two 20: 55:"Conditional probability table" 31:needs additional citations for 944:=0 column that have the value 840:joint probability distribution 721: 669: 430:{\displaystyle x_{2},\,x_{3}.} 321: 300: 248: 1: 960:equalling 0 or 1 given that 1078: 773:matrix. This matrix is a 570:states for each variable 313:– where the vertical bar 135:conditional probabilities 1062:Conditional probability 464:cells. In general, for 817: 747: 647: 594: 593:{\displaystyle x_{i},} 564: 537: 478: 458: 431: 387: 360: 329: 307: 232: 205: 185: 842:given in this table: 818: 748: 648: 595: 565: 563:{\displaystyle K_{i}} 538: 479: 459: 457:{\displaystyle K^{3}} 432: 388: 386:{\displaystyle x_{1}} 361: 359:{\displaystyle a_{k}} 330: 308: 233: 231:{\displaystyle x_{1}} 206: 186: 922:marginal probability 781: 663: 604: 574: 547: 488: 468: 441: 397: 370: 343: 317: 242: 215: 195: 142: 40:improve this article 1040:Murphy, KP (2012). 813: 793: 743: 643: 590: 560: 533: 474: 454: 427: 383: 356: 325: 303: 228: 201: 181: 1016: 1015: 902: 901: 784: 775:stochastic matrix 765:values, create a 477:{\displaystyle M} 328:{\displaystyle |} 204:{\displaystyle K} 116: 115: 108: 90: 1069: 1046: 1045: 1044:. The MIT Press. 1037: 971: 845: 829:binary variables 822: 820: 819: 814: 806: 805: 792: 752: 750: 749: 744: 739: 738: 720: 719: 707: 706: 694: 693: 681: 680: 652: 650: 649: 644: 639: 638: 626: 625: 616: 615: 599: 597: 596: 591: 586: 585: 569: 567: 566: 561: 559: 558: 542: 540: 539: 534: 532: 531: 513: 512: 500: 499: 483: 481: 480: 475: 463: 461: 460: 455: 453: 452: 436: 434: 433: 428: 423: 422: 409: 408: 392: 390: 389: 384: 382: 381: 366:of the variable 365: 363: 362: 357: 355: 354: 339:possible values 334: 332: 331: 326: 324: 312: 310: 309: 304: 299: 298: 286: 285: 273: 272: 260: 259: 237: 235: 234: 229: 227: 226: 210: 208: 207: 202: 190: 188: 187: 182: 180: 179: 167: 166: 154: 153: 131:random variables 111: 104: 100: 97: 91: 89: 48: 24: 16: 1077: 1076: 1072: 1071: 1070: 1068: 1067: 1066: 1052: 1051: 1050: 1049: 1039: 1038: 1034: 1029: 995:P(y=1 given x) 984:P(y=0 given x) 794: 779: 778: 727: 711: 698: 685: 672: 661: 660: 630: 617: 607: 602: 601: 577: 572: 571: 550: 545: 544: 523: 504: 491: 486: 485: 466: 465: 444: 439: 438: 437:This table has 414: 400: 395: 394: 373: 368: 367: 346: 341: 340: 315: 314: 290: 277: 264: 251: 240: 239: 218: 213: 212: 193: 192: 191:where each has 171: 158: 145: 140: 139: 112: 101: 95: 92: 49: 47: 37: 25: 12: 11: 5: 1075: 1073: 1065: 1064: 1054: 1053: 1048: 1047: 1031: 1030: 1028: 1025: 1014: 1013: 1010: 1007: 1003: 1002: 999: 996: 992: 991: 988: 985: 981: 980: 977: 974: 952:=1 given that 900: 899: 896: 893: 890: 886: 885: 882: 879: 876: 872: 871: 868: 865: 862: 858: 857: 854: 851: 848: 812: 809: 804: 801: 797: 791: 787: 742: 737: 734: 730: 726: 723: 718: 714: 710: 705: 701: 697: 692: 688: 684: 679: 675: 671: 668: 642: 637: 633: 629: 624: 620: 614: 610: 589: 584: 580: 557: 553: 530: 526: 522: 519: 516: 511: 507: 503: 498: 494: 473: 451: 447: 426: 421: 417: 412: 407: 403: 380: 376: 353: 349: 323: 302: 297: 293: 289: 284: 280: 276: 271: 267: 263: 258: 254: 250: 247: 225: 221: 200: 178: 174: 170: 165: 161: 157: 152: 148: 114: 113: 28: 26: 19: 13: 10: 9: 6: 4: 3: 2: 1074: 1063: 1060: 1059: 1057: 1043: 1036: 1033: 1026: 1024: 1020: 1011: 1008: 1005: 1004: 1000: 997: 994: 993: 989: 986: 983: 982: 978: 975: 973: 972: 969: 967: 963: 959: 955: 951: 947: 943: 939: 935: 931: 927: 923: 919: 915: 911: 907: 897: 894: 891: 888: 887: 883: 880: 877: 874: 873: 869: 866: 863: 860: 859: 855: 852: 849: 847: 846: 843: 841: 837: 833: 830: 826: 810: 807: 802: 799: 795: 789: 785: 776: 772: 768: 764: 761:ranging over 760: 756: 740: 735: 732: 728: 724: 716: 712: 708: 703: 699: 695: 690: 686: 682: 677: 673: 666: 658: 653: 640: 635: 631: 627: 622: 618: 612: 608: 587: 582: 578: 555: 551: 528: 524: 520: 517: 514: 509: 505: 501: 496: 492: 471: 449: 445: 424: 419: 415: 410: 405: 401: 378: 374: 351: 347: 338: 295: 291: 287: 282: 278: 274: 269: 265: 261: 256: 252: 245: 223: 219: 198: 176: 172: 168: 163: 159: 155: 150: 146: 136: 132: 129: 125: 121: 110: 107: 99: 96:December 2013 88: 85: 81: 78: 74: 71: 67: 64: 60: 57: –  56: 52: 51:Find sources: 45: 41: 35: 34: 29:This article 27: 23: 18: 17: 1041: 1035: 1021: 1017: 965: 961: 957: 953: 949: 945: 941: 937: 933: 929: 925: 917: 913: 909: 905: 903: 835: 831: 824: 770: 766: 762: 758: 754: 654: 336: 123: 117: 102: 93: 83: 76: 69: 62: 50: 38:Please help 33:verification 30: 133:to display 1027:References 484:variables 120:statistics 66:newspapers 838:have the 786:∑ 696:∣ 628:⋯ 518:… 275:∣ 128:dependent 1056:Category 823:for all 916:=0 and 80:scholar 657:matrix 122:, the 82:  75:  68:  61:  53:  936:that 934:given 924:that 889:P(x) 856:P(y) 753:with 543:with 87:JSTOR 73:books 1006:Sum 1001:2/3 990:1/3 979:x=1 908:and 884:4/9 875:y=1 870:5/9 861:y=0 834:and 757:and 59:news 998:2/6 987:4/6 976:x=0 932:=0 895:3/9 892:6/9 881:2/9 878:2/9 867:1/9 864:4/9 853:x=1 850:x=0 118:In 42:by 1058:: 1012:1 968:: 898:1 1009:1 966:y 962:x 958:y 954:x 950:y 946:y 942:x 938:x 930:y 926:x 918:y 914:x 910:y 906:x 836:y 832:x 825:j 811:1 808:= 803:j 800:k 796:T 790:k 771:K 769:× 767:K 763:K 759:j 755:k 741:, 736:j 733:k 729:T 725:= 722:) 717:j 713:b 709:= 704:2 700:x 691:k 687:a 683:= 678:1 674:x 670:( 667:P 641:. 636:M 632:K 623:2 619:K 613:1 609:K 588:, 583:i 579:x 556:i 552:K 529:M 525:x 521:, 515:, 510:2 506:x 502:, 497:1 493:x 472:M 450:3 446:K 425:. 420:3 416:x 411:, 406:2 402:x 379:1 375:x 352:k 348:a 337:K 322:| 301:) 296:3 292:x 288:, 283:2 279:x 270:k 266:a 262:= 257:1 253:x 249:( 246:P 224:1 220:x 199:K 177:3 173:x 169:, 164:2 160:x 156:, 151:1 147:x 109:) 103:( 98:) 94:( 84:· 77:· 70:· 63:· 36:.

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"Conditional probability table"
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Conditional probability

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