The WinBUGS package is a convenient method for carrying out a Bayesian analysis for models containing many variables that can be expressed as a DAG. The model is easily specified in a graphical form by drawing the DAG and specifying distributions and relationships between nodes. While the package can not be used for the more complicated circumstances encountered for the growth model, due to the computational complexity introduced by the integration of the differential equation to obtain mean length, the coalescence model is very tractable.