Interequation Constraint and the Specification of Dynamic Structure

This note considers the effect of a class of linear inter-equation constraints in the specification of the lag structure in econometric models. In particular, attention is focused on the linear summing, or "adding up�, constraints which arise between equations in factor shares analysis. The consequences of such constraints on the specification of lag structures for models with dynamic adjustments and autoregressive or moving-average disturbances are presented in the form of linear restrictions which result in singular coefficient matrices . Thus, the structural (lag) specification of one equation depends on the structure of all other equations in the model.