MUDAS stands for Model of an Uncertain Dryland Agricultural System. It is a discrete stochastic version of MIDAS that deals with season and price variability as well as with farmers attitudes to income risk. Its development in the late 1980's (Morrison et al. 1986; Kingwell, 1987; Kingwell et al., 1990; Kingwell et al., 1993; Kingwell, 1994) was stimulated by the criticism of MIDAS that it did not allow for risk. MUDAS not only provides a deeper insight into the farming system, but it also allows for biases resulting from the simplifications inherent in MIDAS to be tested.

MUDAS describes a typical farm in the eastern wheatbelt of Western Australia. As expected, the gross elements of the farming strategy (i.e., the types of rotations practiced, the levels of different enterprises) are reasonably consistent between MIDAS and MUDAS. In addition to this, the latter model includes eleven discrete season types with a wide range of options for tactical adjustments in each. Although the core strategy is the same every year, tactical adjustments can be made in each season type according to climatic conditions before sowing. These tactical adjustments also have carry-over effects on costs, yields and responses to inputs in subsequent years. Thus the model fully captures inter-year effects in calculating an optimal equilibrium solution. MUDAS includes approximately 1400 activities and 1200 constraints and, like MIDAS, uses MARG (Pannell, 1990) to process the outputs from the AESOP linear programming package.