A stochastic simulation model was developed to assess the risk of H5N1 spreading along the market chain through
the movement of live poultry. The model was written in MapBasic (Pitney Bowes MapInfo) and operates in MapInfo
(MapInfo Professional Version 11.5, Pitney Bowes MapInfo). To quantify risk, the program uses Monte Carlo
methods to sample probability distributions to set a number of input parameters. For each iteration the model
randomly draws numbers from the input distributions and over multiple iterations a distribution of output values is
produced that reflects both chance and uncertainty (Horst et al., 1999).