The Generalized Method of Moments in the Bayesian Framework and a Model of Moment Selection Criterion

While the classical framework has a rich set of limited information procedures such as GMM and other related methods, the situation is not so in the Bayesian framework. We develop a limited information procedure in the Bayesian framework that does not require the knowledge of the likelihood function. The developed procedure is a Bayesian counterpart of the classical GMM but has advantages over the classical GMM in practical applications. The necessary limited information for our approach is a set of moment conditions, instead of the likelihood function, which has a counterpart in the classical GMM. Such moment conditions in the Bayesian framework are obtained from the equivalence condition of the Bayes' estimator and the GMM estimator. From such moment conditions, a posterior probability measure is derived that forms the basis of our limited information Bayesian procedure. This limited information posterior has some desirable properties for small and large sample analyses. An alternative approach is also provided in this paper for deriving a limited information posterior based on a variant of the empirical likelihood method where an empirical likelihood is obtained from the moment conditions of GMM. This alternative approach yields asymptotically the same result as the approach explained above. Based on our limited information method, we develop a procedure for selecting the moment for GMM. This moment selection procedure is an extension of the Bayesian model selection procedure to the Bayesian semi-parametric, limited information framework. It is shown that under some conditions the proposed moment selection procedure is a consistent decision rule.

Discrete denoising of heterogenous two-dimensional data

We consider discrete denoising of two-dimensional data with characteristics that may be varying abruptly between regions. Using a quadtree decomposition technique and space-filling curves, we extend the recently developed S-DUDE (Shifting Discrete Universal DEnoiser), which was tailored to one-dimensional data, to the two-dimensional case. Our scheme competes with a genie that has access, in addition to the noisy data, also to the underlying noiseless data, and can employ $m$ different two-dimensional sliding window denoisers along $m$ distinct regions obtained by a quadtree decomposition with $m$ leaves, in a way that minimizes the overall loss. We show that, regardless of what the underlying noiseless data may be, the two-dimensional S-DUDE performs essentially as well as this genie, provided that the number of distinct regions satisfies $m=o(n)$, where $n$ is the total size of the data. The resulting algorithm complexity is still linear in both $n$ and $m$, as in the one-dimensional case. Our experimental results show that the two-dimensional S-DUDE can be effective when the characteristics of the underlying clean image vary across different regions in the data.Comment: 16 pages, submitted to IEEE Transactions on Information Theor

Economic and Political Changes and Import Demand Behavior of North Korea

We study some empirical aspects of North Korean economy implied in its import behavior in the period before the collapse of Soviet Union. Our analysis is based on econometric inference for a cointegration relation and some model determination methods. We have found that for North Korean economy some non-market factors are important determinants of the import behavior. The non-market factors are related to the country¡¯s political situations, its political relation with two communist superpowers, and its relation with western industrialized countries. Our results show that the non-market factors have different impacts on imports from different countries and imports for different commodity groups, which enables us to find some interesting aspects of North Korean economy. Among several results those with the following two implications are of particular interests. First, the two communist superpowers were overall stable and the most important suppliers to North Korean economy regardless of the political situation while Western countries filled the deficiency, if any, caused by Sino-Soviet dispute. Second, the foreign debt problem had significantly negative impacts on imports from the capitalist countries, which is true even after the new open door policy initiated in 1984.

End-of-Sample Cointegration Breakdown Tests

This paper introduces tests for cointegration breakdown that may occur over a relatively short time period, such as at the end of the sample. The breakdown may be due to a shift in the cointegrating vector or due to a shift in the errors from being I(0) to being I(1). Tests are introduced based on the post-breakdown sum of squared residuals and the post-breakdown sum of squared reverse partial sums of residuals. Critical values are provided using a parametric subsampling method. The regressors in the model are taken to be arbitrary linear combinations of deterministic, stationary, and integrated random variables. The tests are asymptotically valid when the number of observations in the breakdown period, m, is fixed and finite as the total sample size, T+m, goes to infinity. The tests are asymptotically valid under weak conditions. Simulation results indicate that the tests work well in the scenarios considered. Use of the tests is illustrated by testing for interest rate parity breakdown during the Asian financial crisis of 1997.Cointegration, Least squares estimator, Model breakdown, Parameter change test, Structural change

Who Is Caring for the Caregiver? The Role of Cybercoping for Dementia Caregivers

The purpose of this study is to investigate the relationship between dementia caregivers’ communication behaviors (information seeking and forwarding) and their outcomes (coping outcomes: e.g., dealing better with negative feelings or improved medical outcomes). A survey data set of dementia patients’ caregivers substantiates the effects of communication behaviors about dementia illness on coping outcomes, as well as the mediating role of emotion-focused and problem-focused coping processes. Using structural equation modeling (SEM), this study found positive effects of communication behaviors on outcomes through coping processes. Further, the results indicate that communication behaviors in cyberspace are crucial for caregivers to cope with dementia, both affectively (improvement of caregivers’ emotional control) and physically (health improvement of patients). The implications for the improvement of public health through online health communication behaviors are discussed

Form Factors for Exclusive Semileptonic BB--Decays

We developed the new parton model approach for exclusive semileptonic decays of $B$-meson to $D,~D^*$ by extending the inclusive parton model, and by combining with the results of the HQET, motivated by Drell-Yan process. Without the nearest pole dominance ans\"atze, we {\bf derived} the dependences of hadronic form factors on $q^2$. We also calculated numerically the slope of the Isgur-Wise function, which is consistent with the experimental results.Comment: 20 pages, RevTex, 2 ps figure files(uuencoded in seperate file