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Estimation Bias in Spatial Models with Strongly Connected Weight Matrices
Author(s) -
Smith Tony E.
Publication year - 2009
Publication title -
geographical analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.773
H-Index - 65
eISSN - 1538-4632
pISSN - 0016-7363
DOI - 10.1111/j.1538-4632.2009.00758.x
Subject(s) - range (aeronautics) , mathematics , dependency (uml) , lag , spatial dependence , statistics , statistical physics , computer science , physics , artificial intelligence , computer network , materials science , composite material
This article shows that, for both spatial lag and spatial error models with strongly connected weight matrices, maximum likelihood estimates of the spatial dependence parameter are necessarily biased downward . In addition, this bias is shown to be present in general Moran tests of spatial dependency. Thus, positive dependencies may often fail to be detected when weight matrices are strongly connected. The analysis begins with a detailed examination of downward bias for the extreme case of maximally connected weight matrices. Results for this case are then extended by continuity to a broader range of (appropriately defined) strongly connected matrices. Finally, a simulated numerical example is presented to illustrate some of the practical consequences of these biases.