Secondary Products, By-products and the Commodity Technology Assumption

A more general method for preparing commodity-by-commodity input-output tables under the commodity technology assumption is presented for the case when there are produced and non-produced by-products, originating in principal and in secondary production. Existing methods of the same family are shown to be special cases of the method presented here. An incorrect model specification is found to be a sufficient condition for unwarranted negative coefficients. Finally, the model is shown to satisfy desirable properties of an input-output system