Selecting the normal population with largest (Smallest) value of mahalanobis distance from the origin

In this paper the problem of selecting the best of several normal populations in terms of Mahalanobis distance (MD) whenpopulation variance-covariance matrices are equal and unknown is discussed. The selection rule enunciated is shown to ap-proximately satisfy the usual requirement of a minimum guaranteed probability of correct selection. Methods of computing tables required for application of the rule are discussed.     

The nearest proportional to size sampling design

The construction of a proportional to size sampling design nearest to a given design is introduced. The realization of the new design can be easily made with the help of the original one.     

The overlapping coefficient as a measure of agreement between probability distributions and point estimation of the overlap of two normal densities

The overlapping coefficient is defined as a measure of the agreement between two probability distributions. Its relationship to the dissimilarity index and its propertie are described. An extensive treatment of maximum-likelihood estimation of the overlap between two normal distributions is presented as an example of estimating the overlapping coefficient from sample data.     

Outlier detection for high dimensional data using the Comedian approach

The process of detection of outliers is an interesting and important aspect in the analysis of data, as it could impact the inference. There are various methods available in the literature for detection of outliers in multivariate data [V. Barnett and T. Lewis, Outliers in Statistical Data, John Wiley & Sons, Chichester, 1994] using the Mahalanobis distance measure. An attempt is made to propose an alternate method of outlier detection based on the comedian introduced by Falk [On MAD and Comedians, Ann. Inst. Statist. Math. 49 (1997), pp. 615–644]. The proposed method is computationally efficient with high breakdown value and low computation time. Further, important properties, namely, success rates (SR) and false detection rates (FDR) are studied and compared with some of the well-known outlier detection methods through a simulation study. The Comedian method has high SR and low FDR for all combination of parameters. On removal of the detected outliers or down weighing, the same, highly robust and approximately affine equivariant estimators of multivariate location and scatter can be obtained. Finally, the method is applied to well-known real data sets to evaluate its performance.     

Pena's statistic for the Liu regression

In fitting regression model, one or more observations may have substantial effects on estimators. These unusual observations are precisely detected by a new diagnostic measure, Pena's statistic. In this article, we introduce a type of Pena's statistic for each point in Liu regression. Using the forecast change property, we simplify the Pena's statistic in a numerical sense. It is found that the simplified Pena's statistic behaves quite well as far as detection of influential observations is concerned. We express Pena's statistic in terms of the Liu leverages and residuals. The normality of this statistic is also discussed and it is demonstrated that it can identify a subset of high Liu leverage outliers. For numerical evaluation, simulated studies are given and a real data set has been analysed for illustration.     

Testing Independence of Covariates and Errors in Non‐parametric Regression

Consider a non‐parametric regression model Y =m (X )+ϵ , where m is an unknown regression function, Y is a real‐valued response variable, X is a real covariate, and ϵ is the error term. In this article, we extend the usual tests for homoscedasticity by developing consistent tests for independence between X and ϵ . Further, we investigate the local power of the proposed tests using Le Cam's contiguous alternatives. An asymptotic power study under local alternatives along with extensive finite sample simulation study shows that the performance of the new tests is competitive with existing ones. Furthermore, the practicality of the new tests is shown using two real data sets.     

Scalable Bayes under Informative Sampling

Bayesian hierarchical formulations are utilized by the U.S. Bureau of Labor Statistics (BLS) with respondent‐level data for missing item imputation because these formulations are readily parameterized to capture correlation structures. BLS collects survey data under informative sampling designs that assign probabilities of inclusion to be correlated with the response on which sampling‐weighted pseudo posterior distributions are estimated for asymptotically unbiased inference about population model parameters. Computation is expensive and does not support BLS production schedules. We propose a new method to scale the computation that divides the data into smaller subsets, estimates a sampling‐weighted pseudo posterior distribution, in parallel, for every subset and combines the pseudo posterior parameter samples from all the subsets through their mean in the Wasserstein space of order 2. We construct conditions on a class of sampling designs where posterior consistency of the proposed method is achieved. We demonstrate on both synthetic data and in application to the Current Employment Statistics survey that our method produces results of similar accuracy as the usual approach while offering substantially faster computation.     

Sufficient dimension reduction via distance covariance with multivariate responses

In this article, we propose a new method for sufficient dimension reduction when both response and predictor are vectors. The new method, using distance covariance, keeps the model-free advantage, and can fully recover the central subspace even when many predictors are discrete. We then extend this method to the dual central subspace, including a special case of canonical correlation analysis. We illustrated estimators through extensive simulations and real datasets, and compared to some existing methods, showing that our estimators are competitive and robust.     

The Rate of Convergence of some Asymptotic Expansions for Distribution Approximations via an Esseen Type Estimate

Some asymptotic expansions not necessarily related to the central limit theorem are studied. We first observe that the smoothing inequality of Esseen implies the proximity, in the Kolmogorov distance sense, of the distributions of the random variables of two random sequences satisfying a sort of general asymptotic relation. We then present several instances of this observation. A first example, partially motivated by the the statistical theory of high precision measurements, is given by a uniform asymptotic approximation to (g(X + μ _n )) _n∈?, where g is some smooth function, X is a random variable and (μ _n ) _n∈? is a sequence going to infinity; a multivariate version is also stated and proved. We finally present a second class of examples given by a randomization of the interesting parameter in some classical asymptotic formulas; namely, a generic Laplace's type integral, randomized by the sequence (μ _n X) _n∈?, X being a Gamma distributed random variable.     

The impact of distance on acquisition performance

A challenge in interpreting research is that the construct of ‘distance’ has multiple dimensions that influence acquisition performance. We expand Ghemawat's (2001) typology of distance with its dimensions of cultural, administrative, geographic, and economic distance (CAGE) from a review of 61 empirical research studies of how distance affects acquisition performance. We identify different impacts of distance dimensions on acquisition performance to find that distance dimensions are interdependent. As a result, context matters, when considering the impact of distance on acquisition performance. Supporting institutional theory, the direction of distance may matter, as the results may be different for acquirers in developed and emerging economies. Additional implications for research and management practice are identified.