The effect of mixing-distribution misspecification in conjugate mixture models

Parametric mixture models are commonly used in the analysis of clustered data. Parametric families are specified for the conditional distribution of the response variable given a cluster-specific effect, and for the marginal distribution of the cluster-specific effects. This latter distribution is referred to as the mixing distribution. If the form of the mixing distribution is misspecified, then Bayesian and maximum-likelihood estimators of parameters associated with either distribution may be inconsistent. The magnitude of the asymptotic bias is investigated, using an approximation based on infinitesimal contamination of the mixing distribution. The approximation is useful when there is a closed-form expression for the marginal distribution of the response under the assumed mixing distribution, but not under the true mixing distribution. Typically this occurs when the assumed mixing distribution is conjugate, meaning that the conditional distribution of the cluster-specific parameter given the response variable belongs to the same parametric family as the mixing distribution.     

Policy simulations with a macroeconometric model of the Indian economy

In this paper, the results of various dynamic policy simulations are analyzed within the context of a macroeconometric model of the Indian economy. The model contains 35 equations and offers a consistent framework for policy analysis. It is considerably expanded on the side of the fiscal sector and usefully incorporates the interdependence between monetary and fiscal sectors and gives due attention to supply side considerations. Magnitudes of effects of sustained policy changes are analyzed for the period 1964–1965 to 1974–1975. Impact multipliers and elasticities are also analyzed. Government expenditures variables and deficit financing are shown to have substantial impact on the system whereas changes in tax-rates, discount-rates, and liquidity ratios for commercial banks are shown to have only a marginal impact. The model is used for exploring the growth potential of the economy in a forecast period of five years under alternative assumptions regarding policy options.     

韩国新一轮产业结构调整及其对我国经济结构调整的启示

20世纪90年代以来,韩国经济发展速度放慢的一个重要原因,就是产业结构调整的滞后。目前,韩国正在进行新一轮的产业结构调整,并且初见成效。研究并借鉴韩国产业结构调整的得失,对正处于经济结构调整关键时期的中国来说,大有裨益。     

Binary-image restoration

We consider the problem of binary-image restoration. The image being restored is not random, and we make no assumption about the nature of its contents. The estimate of the colour at each site is a fixed (the same for all sites) function of the data available in a neighbourhood of that site. Under this restriction, the estimate minimizing the overall mean squared error of prediction is the conditional expectation of the true colour given the observations in the neighbourhood of a site. The computation of this conditional expectation leads to the formal definition of the local characteristics of an image, namely, the frequency with which each pattern appears in the true unobserved image. When the “true” distribution of the patterns is unknown, it can be estimated from the records. The conditional expectation described above can then be evaluated using the estimated distribution of the patterns, and this procedure leads to a very natural estimate of the colour at each site. We propose two unbiased and consistent estimates for the distribution of patterns when the noise is a Gaussian white noise. Since the size of realistic images is very large, the estimated pattern distribution is usually close to the true one. This suggests that the estimated conditional expectation can be expected to be nearly optimal. An interesting feature of the proposed restoration methods is that they do not require prior knowledge of the local or global properties of the true underlying image. Several examples based on synthetic images show that the new methods perform fairly well for a variety of images with different degrees of colour continuity or textures.     

Asymptotical improvement of maximum likelihood estimators on Kullback–Leibler loss

We discuss the general form of a first-order correction to the maximum likelihood estimator which is expressed in terms of the gradient of a function, which could for example be the logarithm of a prior density function. In terms of Kullback–Leibler divergence, the correction gives an asymptotic improvement over maximum likelihood under rather general conditions. The theory is illustrated for Bayes estimators with conjugate priors. The optimal choice of hyper-parameter to improve the maximum likelihood estimator is discussed. The results based on Kullback–Leibler risk are extended to a wide class of risk functions.     

韩剧热播的社会效益及对中国电视剧的启示

近年来，韩国电视剧在儒家文化圈，特别是在中国传媒市场上呈现强劲趋势，给韩国带来了巨大的经济收益，带动了众多相关产业，甚至扭转了其他国家对韩民族的文化偏见。探讨韩剧如何火爆，对中国电视剧的发展有一定的启示。     

Estimation of parameters in survey sampling: Optimality

Some recent works on estimation in survey sampling are analyzed and extended from the perspective of the theory of optimal estimating functions.     

Exchange rate policies simulated by means of a disequilibrium model of the Finnish economy

In this paper a model for the Finnish economy with disequilibrium in the goods and financial markets is specified and estimated by single equation methods. The transmission mechanisms of the model are studied in the framework of various devaluation simulations. The model is very sensitive, especially with respect to the prevailing credit market regime and possible regime changes. Policy effects are not so much affected by conditions in the goods market, assuming moderate policy shocks. These considerations suggest the importance in policy planning of identifying the regimes prevailing in the markets.     

Whose rights are they anyway?: The supreme court and the rights of Juveniles

This article examines selected United States Supreme Court decisions from 1923 through the 1984 term of the Court. The selection, which includes Wisconsin v. Yoder, In re Gault, In re Winship, and Schall v. Martin, traces and illustrates the triangle of interest among parent, child, and state as parens patriae, when the issue raised is the interest of children. The focal question is: Have children been recognized as having their own individual Constitutional rights, or have their rights been merged with those of their parents and/or the state standing in the place of the parents?     

Inference about permutation parameter in large samples

The estimation problem of a permutation parameter on the basis of a random sample of increasing size is considered. A necessary and sufficient condition for the existence of an estimator, asymptotically fully efficient for two different distributions families, is derived. We also study the application of this result to cyclic groups of order two and three.