# OddsPrecision.R
# This demo tests the precision of the odds functions for
# Wallenius' and a Fisher's noncentral hypergeometric distributions
# by calculating the mean of distributions with known odds and then
# estimating the odds from the means.
require(BiasedUrn)
require(stats)
OddsEst <- function(m1, m2, n, odds) {
meanW <- meanWNCHypergeo(m1, m2, n, odds, 1E-9)
oddsEstW <- oddsWNCHypergeo(meanW, m1, m2, n)
meanF <- meanFNCHypergeo(m1, m2, n, odds, 1E-9)
oddsEstF <- oddsFNCHypergeo(meanF, m1, m2, n)
list(Odds=odds, Wallenius.mean = meanW, Fisher.mean = meanF,
Wallenius.estimated.odds = oddsEstW, Fisher.estimated.odds = oddsEstF,
Wallenius.rel.error = (oddsEstW-odds)/odds,
Fisher.rel.error = (oddsEstF-odds)/odds)
}
OddsEst(10, 12, 15, 0.6)
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