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Working with the Data Mi = number of rows in D where the A value = the A value in group i Ni = number of rows in D where the B value = the B value in group i The p-value for the group with index i can then be calculated as follows: Pi = P(X ≥ Ki | R, Ni, Mi) = ∑ P(X = x | R, Ni, Mi); x = Ki, ..., min(Ni, Mi) where X is a random variable with a hypergeometric distribution. In probability theory, this distribution describes the number of successes in a sequence of a certain number of draws from a finite population without replacement. This means that the probability formula can be written as follows: where is the binomial coefficient of n and k. Example: Let us consider a data set D which contains information about the country of origin and the number of cylinders for 18 different cars: Model Origin Cylinders VW 1131 EU 4 Saab 99 EU 4 Chevrolet Impala USA 8 Pontiac Catalina USA 8 Plymouth Fury USA 8 Mercury Monarch USA 6 Buick Century USA 6 Audi 100 EU 4 Renault 12 EU 4 Mercedes 280 EU 6 Chevrolet Caprice USA 8 Oldsmobile Cutlass USA 8 Peugeot 604 EU 6 Pontiac Lemans USA 6 343
