NoncenHypergeom {MCMCpack}R Documentation

The Noncentral Hypergeometric Distribution


Evaluates the density at a single point or all points, and generate random draws from the Noncentral Hypergeometric distribution.


dnoncenhypergeom(x=NA, n1, n2, m1, psi)
rnoncenhypergeom(n, n1, n2, m1, psi)


x The location to evaluate the density. If x is NA, then a matrix is returned with the density evaluated at all possible points.
n The number of draws to make from the distribution.
n1 The size of group one.
n2 The size of group two.
m1 The observed number of positive outcomes (in both groups).
psi Odds ratio.


The Noncentral Hypergeometric is particularly useful for conditional inference for (2 x 2) tables. We use the parameterization and algorithms of Liao and Rosen (2001). The underlying R code is based on their published code. See their article for details of the parameterization.


dnoncenhypergeom evaluates the density at point x, or a matrix with the first column containing the possible values of the random variable, and the second column containing the probabilities. rnoncenhypergeom returns a list of n random draws from the distribution.


J. G. Liao and Ori Rosen. 2001. ``Fast and Stable Algorithms for Computing and Sampling From the Noncentral Hypergeometric Distribution." The American Statistician. 55: 366-369.


  density <- dnoncenhypergeom(NA, 500, 500, 500, 6.0)
  draws <- rnoncenhypergeom(10, 500, 500, 500, 6.0)

[Package MCMCpack version 0.5-2 Index]