On a Problem in Identifying Linear Parametric Models

This paper establishes that when equations connecting coefficients from reduced forms with their structural counterparts are inconsistent, a necessary and sufficient condition standard in econometric textbooks for the identifiability of coefficients in linear simultaneous equations systems is insufficient. In this case,, the identification of those coefficients is not possible unless an additional criterion for choosing among an infinite number of solutions for the unknown structural coefficients occurs naturally as par of the system