Please use this identifier to cite or link to this item: https://hdl.handle.net/10419/64756 
Year of Publication: 
2010
Series/Report no.: 
cemmap working paper No. CWP11/10
Publisher: 
Centre for Microdata Methods and Practice (cemmap), London
Abstract: 
Instrumental variable models for discrete outcomes are set, not point, identifying. The paper characterises identi.ed sets of structural functions when endogenous variables are discrete. Identi.ed sets are unions of large numbers of convex sets and may not be convex nor even connected. Each of the component sets is a projection of a convex set that resides in a much higher dimensional space onto the space in which a structural function resides. The paper develops a symbolic expression for this projection and gives a constructive demonstration that it is indeed the identi.ed set. We provide a MathematicaTM notebook which computes the set symbolically. We derive properties of the set, suggest how the set can be used in practical econometric analysis when outcomes and endogenous variables are discrete and propose a method for estimating identified sets under parametric or shape restrictions. We develop an expression for a set of structural functions for the case in which endogenous variables are continuous or mixed discrete-continuous and show that this set contains all structural functions in the identified set in the non-discrete case.
Subjects: 
Discrete endogenous variables
Discrete outcomes
Endogeneity
Fourier-Motzkin Elimination
Incomplete models
Instrumental variables
Set idenfication
Threshold Crossing Models
JEL: 
C10
C14
C50
C51
Persistent Identifier of the first edition: 
Document Type: 
Working Paper

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