Testing symmetry with a procedure, combining the sign test and the signed rank test

Summary  A procedure for testing symmetry is described which combines the ease of the sign test with the efficiency of the signed rank test.     

Asymptotic optimality of all signed rank tests at infinity

All signed rank tests are proved to have the same optimal BAHADUR efficiency, when the alternative tends to infinity. This result underlines the significance of the classical approach of comparing rank tests under local alternatives (comp. KREMER [7], [8]).     

Data driven rank test for the change point problem

Data driven test procedure for detection of change is introduced and its properties are studied. The new solution is max-type statistic related to data-driven rank tests for two-sample subproblems. Simulations show that the new test possesses high and stable power. The test is consistent at essentially any alternative. Asymptotic null distribution of the test is derived. The work of the first two authors has been partially supported by the grants GAČR 201/06/0186 and MSM 02160839.     

A Wald test for the cointegration rank in nonstationary fractional systems

This paper develops new methods for determining the cointegration rank in a nonstationary fractionally integrated system, extending univariate optimal methods for testing the degree of integration. We propose a simple Wald test based on the singular value decomposition of the unrestricted estimate of the long run multiplier matrix. When the “strength” of the cointegrating relationship is less than 1/2, the test statistic has a standard asymptotic distribution, like Lagrange Multiplier tests exploiting local properties. We consider the behavior of our test under estimation of short run parameters and local alternatives. We compare our procedure with other cointegration tests based on different principles and find that the new method has better properties in a range of situations by using information on the alternative obtained through a preliminary estimate of the cointegration strength.     

On the distribution of the test statistics of Kendall and Wilcoxon's two sample test when ties are present

Zoals bekend is, kan de exacte verdeling van de toetsingsgrootheid van Kendall voor rangcorrelatie als er geen gelijke waarnemingen optreden en ah de nulhypothese juist is, berekend worden met behulp van een recurrente formule. Hetzelfde geldt voor de toetsingsgrootheid van Wilcoxon voor het geval van twee steekproeven. Wanneer er wél gelijke waarnemingen optreden, kan men, zoals hier wordt aangetoond, een gegeneraliseerde recursieformule gebruiken. De berekeningsmethode, die berust op het herhaald toepassen van deze recursieformule, is minder afschrikwekkend dan die welke bestaat in het opstellen van alle mogelijke schema's en de berekening van de bijbehorende kansen.     

On a test of homogeneity for samples from a negative binomial distribution

Summary An exact test is proposed for the equality of probabilities of an event in a series of independent trials, each drawn from a negative binomial distribution with a specified number of successes. The power function of this conditional test is also derived, as well as an approximate test for homogeneity.     

On the two-sided power distribution

This paper concerns a two-parameter two-sided power distribution introduced by van Dorp and Kotz on the interval [0,1]. We introduce a reformulated two-sided power distribution (with the same number of parameters) and provide evidence to prove that it is more flexible than the one suggested by van Dorp and Kotz. We derive various properties of the new distribution as well as provide several hitherto unknown properties of the distribution due to van Dorp and Kotz. We also discuss estimation by the method of moments and the method of maximum likelihood.Received September 2003     

On the distribution of Harter

In his seminal paper, Harter (1951) derived the exact distribution of Wald’s classification statistic. In this note, we consider the more general problem of deriving the exact distribution of the product XY when X and Y are independent student’s t random variables with any degrees of freedom. Our results are simpler and more general than those presented by Harter (1951).     

On the generalized Poisson distribution

We use Euler's difference lemma to prove that, for θ > 0 and 0 ≤λ < 1, the function P _n defined on the non-negative integers by
P _n (θ, λ) = [θ(θ + n λ) ^{n −1}/ n !]e^{− n λ−θ}
defines a probability distribution, known as the Generalized Poisson Distribution.     

On the performance of the tick test

In financial research, the sign of a trade (or identity of trade aggressor) is not always available in the transaction dataset and it can be estimated using a simple set of rules called the tick test. In this paper we investigate the accuracy of the tick test from an analytical perspective by providing a closed formula for the performance of the prediction algorithm. By analyzing the derived equation, we provide formal arguments for the use of the tick test by proving that it is bounded to perform better than chance (50/50) and that the set of rules from the tick test provides an unbiased estimator of the trade signs. On the empirical side of the research, we compare the values from the analytical formula against the empirical performance of the tick test for fifteen heavily traded stocks in the Brazilian equity market. The results show that the formula is quite realistic in assessing the accuracy of the prediction algorithm in a real data situation.     

On the reliability of the chi-square test

Summary The classical ₂ test of goodness of fit depends on the partition chosen to calculate it. In this work the covariance structure of the family of all ₂ tests obtained by translation (modulo 1) of a uniform partition of the interval [0, 1) it is determined, under the hypothesis of uniform distribution on [0, 1). This is used to define and compute an index which measure the indeterminacy of the ₂ test due to the arbitrary choice of the partition to compute it.     

On Riesz distribution

The Riesz distribution for real normed division algebras is derived in this work. Then two versions of these distributions are proposed and some of their properties are studied.     

A curtailed test for the shape parameter of the Weibull distribution

Summary A procedure is proposed in this paper for testing the shape parameter, of the Weibull distribution. The test statistic which is based on the extremal quotient, possesses a monotone property which makes it possible for rejection earlier than the last planned observation of the null hypothesis,H ₀: =₀ when the alternative hypothesis isH _a: <₀ and early acceptance ofH ₀ whenH _a: >₀. The test being scale-free, does not require the scale parameter to be known.     

On the distribution of city sizes

The city size distribution in many countries is remarkably well described by a Pareto distribution. We derive conditions that standard urban models must satisfy in order to explain this regularity. We show that under general conditions urban models must have (i) a balanced growth path and (ii) a Pareto distribution for the underlying source of randomness. In particular, one of the following combinations can induce a Pareto distribution of city sizes: (i) preferences for different goods follow reflected random walks, and the elasticity of substitution between goods is 1; or (ii) total factor productivities of different goods follow reflected random walks, and increasing returns are equal across goods.     

浅论配送半径的计算方法

配送处于供应链的末端,是上游所有工作的承继者,也是供应链最终价值的实现者之一,随着市场需求个性化、多样化、即时化的加剧,供应链与供应链之间的竞争主要聚焦于配送环节,而确定一个科学精确的配送半径,是实现配送中心合理规划和高配送质量的重要保证,文中阐述了影响配送半径的主要因素,给出了计算配送半径的基本方法,引出了保留半径这一新概念,使配送半径的计算更加精确。     

On the distribution of the sample autocorrelation coefficients

Sample autocorrelation coefficients are widely used to test the randomness of a time series. Despite its unsatisfactory performance, the asymptotic normal distribution is often used to approximate the distribution of the sample autocorrelation coefficients. This is mainly due to the lack of an efficient approach in obtaining the exact distribution of sample autocorrelation coefficients. In this paper, we provide an efficient algorithm for evaluating the exact distribution of the sample autocorrelation coefficients. Under the multivariate elliptical distribution assumption, the exact distribution as well as exact moments and joint moments of sample autocorrelation coefficients are presented. In addition, the exact mean and variance of various autocorrelation-based tests are provided. Actual size properties of the Box–Pierce and Ljung–Box tests are investigated, and they are shown to be poor when the number of lags is moderately large relative to the sample size. Using the exact mean and variance of the Box–Pierce test statistic, we propose an adjusted Box–Pierce test that has a far superior size property than the traditional Box–Pierce and Ljung–Box tests.     

On the properties of a multiple sequential test

We consider a multiple testing problem based on an i.i.d. sample of K-dimensional observations. We want to test whether at least one of the unknown means is positive. We propose a sequential test which is of the nature of a multiple truncated sequential probability ratio test. We asymptotically analyse the expected sample size and compare it to the sample sizes which arise when one looks at effects separately.     

An approximation to the limit distribution of the epps-pulley test statistic for normality

Summary The approach of Epps and Pulley (1983) based on the empirical characteristic function is one of the most powerful tools for detecting any departures from normality. We obtain the first four moments of the limiting null distribution of the Epps-Pulley Statistic. Johnson- and Pearson curve fitting yields excellent approximations to simulated quantiles, and by modifying the test statistic the procedure may be carried out easily without the use of extensive tables for all sample sizes. Research done while the author was on leave at the University of Gie?en.     

Bayesian life test planning for the Weibull distribution with given shape parameter

This paper describes Bayesian methods for life test planning with Type II censored data from a Weibull distribution, when the Weibull shape parameter is given. We use conjugate prior distributions and criteria based on estimating a quantile of interest of the lifetime distribution. One criterion is based on a precision factor for a credibility interval for a distribution quantile and the other is based on the length of the credibility interval. We provide simple closed form expressions for the relationship between the needed number of failures and the precision criteria. Examples are used to illustrate the results.Received: October 2002 / Revised: March 2004