Smooth supersaturated models

In areas such as kernel smoothing and non-parametric regression, there is emphasis on smooth interpolation. We concentrate on pure interpolation and build smooth polynomial interpolators by first extending the monomial (polynomial) basis and then minimizing a measure of roughness with respect to the extra parameters in the extended basis. Algebraic methods can help in choosing the extended basis. We get arbitrarily close to optimal smoothing for any dimension over an arbitrary region, giving simple models close to splines. We show in examples that smooth interpolators perform much better than straight polynomial fits and for small sample size, better than kriging-type methods, used, for example in computer experiments.     

Using balanced iterative reducing and clustering hierarchies to compute approximate rank statistics on massive datasets

The balanced iterative reducing and clustering hierarchies (BIRCH) algorithm handles massive datasets by reading the data file only once, clustering the data as it is read, and retaining only a few clustering features to summarize the data read so far. Using BIRCH allows to analyse datasets that are too large to fit in the computer main memory. We propose estimates of Spearman's ρ and Kendall's τ that are calculated from a BIRCH output and assess their performance through Monte Carlo studies. The numerical results show that the BIRCH-based estimates can achieve the same efficiency as the usual estimates of ρ and τ while using only a fraction of the memory otherwise required.     

A more efficient mean estimator for judgement post-stratification

Meeden and Lee [More efficient inferences using ranking information obtained from judgment sampling. J Surv Stat Methodol. 2014;2:38–57] recently showed that one can improve upon the standard unbiased mean estimator for judgement post-stratification (JPS) by using the ordering information in the sample. We propose an alternate mean estimator that uses this same information. This alternate estimator is far simpler to compute than the estimator of Meeden and Lee (2014), and we show through simulations that it typically outperforms the Meeden and Lee (2014) estimator in cases where the rankings are sufficiently good that JPS is useful.     

Bayesian estimation and prediction based on generalized Type-II hybrid censored sample

ABSTRACT

In this paper, we consider a general form for the underlying distribution and a general conjugate prior, and develop a general procedure for deriving the maximum likelihood and Bayesian estimators based on an observed generalized Type-II hybrid censored sample. The problems of predicting the future order statistics from the same sample and that from a future sample are also discussed from a Bayesian viewpoint. For the illustration of the developed results, the exponential and Pareto distributions are used as examples. Finally, two numerical examples are presented for illustrating all the inferential procedures developed here.     

Effects of nonnormality on the spart for the correlation coefficient: bivariate edgeworth series distribution

The effects of sampling from the bivariate Edgeworth series distribution (BVESD) on the sequential probability ratio test (SPRT) for the correlation coefficient are assessed. The values of the average sample number (ASN) and the operating characteristic (OC) are determined by simulation from such populations. The robustness of the SPRT to this type of nonnormality is demonstrated.     

Efficient computation of the performance of bootstrap and jackknife estimators of the variance of L-statistics

Calculation of the bootstrap and the jackknife estimators of the variance of a statistic often relies on approximation techniques because the exact values are difficult if not impossible to obtain analytically. For the special case where the statistic is a linear combination of order statistics we propose to calculate the exact values combinatorically, thus completely eliminating the second-stage simulation error.     

Advantages of Variance Stabilization

Abstract. Variance stabilization is a simple device for normalizing a statistic. Even though its large sample properties are similar to those of studentizing, many simulation studies of confidence interval procedures show that variance stabilization works better for small samples. We investigated this question in the context of testing a null hypothesis involving a single parameter. We provide support for a measure of evidence for an alternative hypothesis that is simple to compute, calibrate and interpret. It has applications in most routine problems in statistics, and leads to more accurate confidence intervals, estimated power and hence sample size calculations than standard asymptotic methods. Such evidence is readily combined when obtained from different studies. Connections to other approaches to statistical evidence are described, with a notable link to Kullback–Leibler symmetrized divergence.     

A simple nonparametric test for bivariate symmetry about a line

Over the years many researchers have dealt with testing the hypotheses of symmetry in univariate and multivariate distributions in the parametric and nonparametric setup. In a multivariate setup, there are several formulations of symmetry, for example, symmetry about an axis, joint symmetry, marginal symmetry, radial symmetry, symmetry about a known point, spherical symmetry, and elliptical symmetry among others. In this paper, for the bivariate case, we formulate a concept of symmetry about a straight line passing through the origin in a plane and accordingly develop a simple nonparametric test for testing the hypothesis of symmetry about a straight line. The proposed test is based on a measure of deviance between observed counts of bivariate samples in suitably defined pairs of sets. The exact null distribution and non-null distribution, for specified classes of alternatives, of the test statistics are obtained. The null distribution is tabulated for sample size from n=5 up to n=30. The null mean, null variance and the asymptotic null distributions of the proposed test statistics are also obtained. The empirical power of the proposed test is evaluated by simulating samples from the suitable class of bivariate distributions. The empirical findings suggest that the test performs reasonably well against various classes of asymmetric bivariate distributions. Further, it is advocated that the basic idea developed in this work can be easily adopted to test the hypotheses of exchangeability of bivariate random variables and also bivariate symmetry about a given axis which have been considered by several authors in the past.     

Pitman closeness of record values from two sequences to population quantiles

Suppose upper records from two independent sequences from iid continuous random variables from the same distribution are observed. Pitman's measure of closeness of these statistics to population quantiles of the parent distribution is studied and various exact expressions are derived. For symmetric distributions, Pitman closeness probabilities of records to median are also obtained. Examples including exponential and uniform distributions are discussed. Numerical evaluations are presented to illustrate all the results developed here.