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Contingency table
A contingency table is input to this routine. Rows represent the different states of one nominal variable, columns represent the states of another nominal variable, and cells contain the counts of occurrences of that specific state (row, column) of the two variables. A measure and probability of association of the two variables (based on Chi-square) is then given.
For example, rows may represent taxa and columns samples as usual (with specimen counts in the cells). The contingency table analysis then gives information on whether the two variables of taxon and locality are associated. If not, the data matrix is not very informative. For details, see Press et al. (1992).
Reference
Press, W.H., S.A. Teukolsky, W.T. Vetterling & B.P. Flannery. 1992. Numerical Recipes in C. Cambridge University Press.