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Comparing the performance of two indices for spatial model selection: application to two mortality data.

Abstract：

:The statistical analysis of spatially correlated data has become an important scientific research topic lately. The analysis of the mortality or morbidity rates observed at different areas may help to decide if people living in certain locations are considered at higher risk than others. Once the statistical model for the data of interest has been chosen, further effort can be devoted to identifying the areas under higher risks. Many scientists, including statisticians, have tried the conditional autoregressive (CAR) model to describe the spatial autocorrelation among the observed data. This model has greater smoothing effect than the exchangeable models, such as the Poisson gamma model for spatial data. This paper focuses on comparing the two types of models using the index LG, the ratio of local to global variability. Two applications, Taiwan asthma mortality and Scotland lip cancer, are considered and the use of LG is illustrated. The estimated values for both data sets are small, implying a Poisson gamma model may be favoured over the CAR model. We discuss the implications for the two applications respectively. To evaluate the performance of the index LG, we also compute the Bayes factor, a Bayesian model selection criterion, to see which model is preferred for the two applications and simulation data. To derive the value of LG, we estimate its posterior mode based on samples derived from the BUGS program, while for Bayes factor we use the double Laplace-Metropolis method, Schwarz criterion, and a modified harmonic mean for approximations. The results of LG and Bayes factor are consistent. We conclude that LG is fairly accurate as an index for selection between Poisson gamma and CAR model. When easy and fast computation is of concern, we recommend using LG as the first and less costly index.

journal_name

Stat Med

journal_title

Statistics in medicine

authors

Hsiao CK,Tzeng JY,Wang CH

doi

10.1002/1097-0258(20000730)19:14<1915::aid-sim503>

subject

Has Abstract

pub_date

2000-07-30 00:00:00

pages

1915-30

issue

eissn

0277-6715

issn

1097-0258

pii

10.1002/1097-0258(20000730)19:14<1915::AID-SIM503>

journal_volume

pub_type

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Comparing the performance of two indices for spatial model selection: application to two mortality data.