Showing 1 to 10 of 192 matching Articles
Results per page:
Export (CSV)
By
Meintanis, Simos G.; Allison, James; Santana, Leonard
We investigate the finitesample properties of certain procedures which employ the novel notion of the probability weighted empirical characteristic function. The procedures considered are: (1) Testing for symmetry in regression, (2) Testing for multivariate normality with independent observations, and (3) Testing for multivariate normality of random effects in mixed models. Along with the new tests alternative methods based on the ordinary empirical characteristic function as well as other more well known procedures are implemented for the purpose of comparison.
more …
By
Ng, Hon Keung Tony; Balakrishnan, N.; Panchapakesan, S.
In this paper, we first give an overview of the precedencetype test procedures. Then we propose a nonparametric test based on early failures for the equality of two lifetime distributions against two alternatives concerning the best population. This procedure utilizes the minimal Wilcoxon ranksum precedence statistic (Ng and Balakrishnan, 2002, 2004) which can determine the difference between populations based on early (100q%) failures. Hence, this procedure can be useful in lifetesting experiments in biological as well as industrial settings. After proposing the test procedure, we derive the exact null distribution of the test statistic in the twosample case with equal or unequal sample sizes. We also present the exact probability of correct selection under the Lehmann alternative. Then, we generalize the test procedure to the ksample situation. Critical values for some sample sizes are presented. Next, we examine the performance of this test procedure under a locationshift alternative through Monte Carlo simulations. Two examples are presented to illustrate our test procedure with selecting the best population as an objective.
more …
By
Heuchenne, Cédric; PardoFernández, Juan Carlos
Assume that we have two populations (X_{1},Y_{1}) and (X_{2},Y_{2}) satisfying two general nonparametric regression models Y_{j}=m_{j}(X_{j})+ε_{j}, j=1,2, where m(⋅) is a smooth location function, ε_{j} has zero location and the response Y_{j} is possibly rightcensored. In this paper, we propose to test the null hypothesis H_{0}:m_{1}=m_{2} versus the onesided alternative H_{1}:m_{1}<m_{2}. We introduce two test statistics for which we obtain the asymptotic normality under the null and the alternative hypotheses. Although the tests are based on nonparametric techniques, they can detect any local alternative converging to the null hypothesis at the parametric rate n^{−1/2}. The practical performance of a bootstrap version of the tests is investigated in a simulation study. An application to a data set about unemployment duration times is also included.
more …
By
Baragona, Roberto; Battaglia, Francesco ; Cucina, Domenico
Outlier detection and treatment are important steps in exploratory data analysis. A case deletion method in the empirical likelihood framework is suggested here for outlier detection in regression models. The theoretical properties of empirical likelihood hypothesis testing for outlier detection are investigated and asymptotic results are obtained and compared to the empirical likelihood displacement measure. The behavior of our test statistics in finite samples is studied by means of an extensive simulation experiment and some real data sets. A bootstrap version of the test is also proposed, which proves very useful in the case of data far from normality.
more …
By
Melas, Viatcheslav B.; Pepelyshev, Andrey; Shpilev, Petr; Salmaso, Luigi; Corain, Livio; Arboretti, Rosa
Show all (6)
The paper is devoted to the elaboration of an efficient approach for comparison of two regression curves based on the empirical Fourier coefficients of regression functions. For the problem of testing for the equality of the two unknown functions in the case of homoscedastic error structure and observation at equidistant points, we derive a new procedure with adaptive choice of the number of the coefficients used in the hypotheses testing. Our approach is based on approximation of the most powerful test using the full knowledge of the regression functions. The results are justified by theoretical arguments and the superiority of the new procedure is also confirmed by a simulation study.
more …
By
Henze, Norbert; Meintanis, Simos G.
Abstract.
A wide selection of classical and recent tests for exponentiality are discussed and compared. The classical procedures include the statistics of KolmogorovSmirnov and Cramérvon Mises, a statistic based on spacings, and a method involving the score function. Among the most recent approaches emphasized are methods based on the empirical Laplace transform and the empirical characteristic function, a method based on entropy as well as tests of the KolmogorovSmirnov and Cramérvon Mises type that utilize a characterization of exponentiality via the mean residual life function. We also propose a new goodnessoffit test utilizing a novel characterization of the exponential distribution through its characteristic function. The finitesample performance of the tests is investigated in an extensive simulation study.
more …
By
Milošević, Bojana
Two new tests for exponentiality, of integral and Kolmogorovtype, are proposed. They are based on a recent characterization and formed using appropriate Vstatistics. Their asymptotic properties are examined and their local Bahadur efficiencies against some common alternatives are found. A class of locally optimal alternatives for each test is obtained. The powers of these tests, for some small sample sizes, are compared with different exponentiality tests.
more …
By
Bingham, Melissa A. ; Scray, Marissa L.
Although there have been fairly recent advances regarding inference for threedimensional rotation data, there are still many areas of interest yet to be explored. One such area involves comparing the rotational symmetry of 3D rotations. In this paper, nonparametric inference is used to test if F_{1}=F_{2}, where F_{i} is the degree of rotational symmetry of distribution i, through a permutation test. The validity of the developed permutation test is examined through a simulation study and the test is applied to a small example in biomechanics.
more …
By
Meintanis, S. G.
In this paper, goodnessoffit tests are constructed for the skew normal law. The proposed tests utilize the fact that the moment generating function of the skew normal variable satisfies a simple differential equation. The empirical counterpart of this equation, involving the empiricalmoment generating function, yields appropriate test statistics. The consistency of the tests is investigated under general assumptions, and the finitesample behavior of the proposed method is investigated via a parametric bootstrap procedure.
more …
By
Yu, Yuncai; Liu, Xinsheng ; Liu, Ling; Sief, Mohamed
Show all (4)
In this paper, we consider two estimators, a hard thresholding wavelet estimator and a block thresholding wavelet estimator, for the regression function in heteroscedastic nonparametric model with negatively superadditive dependent (NSD) errors. The random design distribution is known or unknown, and the corresponding adaptive properties of these estimators are investigated over Besov spaces, for the
$${L^2}$$
risk. The results indicate that the block thresholding estimator is theoretically and computationally superior to the hard thresholding estimator with the former attains the optimal convergence rates, while the later achieves the nearly optimal convergence rates. Thus the block thresholding estimator provides extensive adaptivity to many irregular function classes even though with the presence of heteroscedastic NSD errors.
more …
