A Note on Algebraic Solutions to Identification

Algebraic methods to establish the identification of structural equation models remain a viable option. However, sometimes it is unclear whether the algebraic solution establishes identification. One example is when there is more than one way to solve for the parameter, but one way leads to a single value and a second way leads to a function with more than one value. This article proves that one explicit and unique solution is sufficient for model identification even when other explicit solutions permit more than one solution. The results are illustrated with an example. The results are useful to attempts to use algebraic means to address model identification.     

MODELING FIRM SPATIAL INTERDEPENDENCE USING NATIONAL DATA COVERAGES: A REGIONAL APPLICATION TO MANURE MANAGEMENT

Abstract A regional modeling framework using national data series is developed to estimate the net cost of land‐applying manure under possible policy provisions to limit water‐ and air‐quality emissions. The modeling framework, applied to the Chesapeake Bay watershed, integrates GIS‐based spatial data within an optimization model to capture spatial effects at a subwatershed scale.