Fishers exact test
a statistical test of independence much used in medical research. It tests the independence of rows and columns in a 2 X 2 contingency table (with 2 horizontal rows crossing 2 vertical columns creating 4 places for data) based on the exact sampling distribution of the observed frequencies. Hence it is an exact test. Devised by the British geneticist and biostatistician R. A. Fisher (1890-1962).