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3 # C O P Y R I G H T N O T I C E #
4 # Copyright (c) 2003-10 by: #
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32 def chiSquare(A, B, C, D):
33 """ Chi-square for a 2x2 table, as described in Gopal Kanji's 100 Statistical Tests
34 note that we only have one degree of freedom, work best if no cell is less than 3.
37 -----------------------------
39 -----------------------------
40 A + C | B + D | A + B + C + D
48 chiN = long(chiAB + chiCD)
50 chiNum = long(chiN - 1) * long(pow(chiAD - chiBC, 2))
51 chiDen = long(chiAB * chiAC * chiBD * chiCD)
53 return long(chiNum / chiDen)