Generate random 2-way tables with given marginals using Patefield's algorithm.
r2dtable(n, r, c)
A list of length
n containing the generated tables as its components.
Patefield, W. M. (1981) Algorithm AS159. An efficient method of generating r x c tables with given row and column totals. Applied Statistics 30, 91--97.
## Fisher's Tea Drinker data. TeaTasting <- matrix(c(3, 1, 1, 3), nrow = 2, dimnames = list(Guess = c("Milk", "Tea"), Truth = c("Milk", "Tea"))) ## Simulate permutation test for independence based on the maximum ## Pearson residuals (rather than their sum). rowTotals <- rowSums(TeaTasting) colTotals <- colSums(TeaTasting) nOfCases <- sum(rowTotals) expected <- outer(rowTotals, colTotals, "*") / nOfCases maxSqResid <- function(x) max((x - expected) ^ 2 / expected) simMaxSqResid <- sapply(r2dtable(1000, rowTotals, colTotals), maxSqResid) sum(simMaxSqResid >= maxSqResid(TeaTasting)) / 1000 ## Fisher's exact test gives p = 0.4857 ...
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