Geographic structure is not yet included in the size model. In both configurations, synthesis maintains a full age-structured description of the population and employs conventional equations to describe the population dynamics. A wide hierarchical range of model complexity can be defined for either version (Methot 1998). At one extreme, the model can be used with no age or size data (with external estimation of selectivity and weight-at-age) and the est imation process can be condensed to a few stock-recruitment parameters that mimic stock-reduction analysis (Kimura and Tagart 1982). On the other extreme, inclusion of a vector of parameters to allow time-varying fishery.
