BACKGROUND Agricultural tractor overturns without rollover protective structures are the leading cause of farm fatalities in the United States. To our knowledge, no studies have incorporated the spatial scan statistic in identifying high-risk areas for tractor overturns. The aim of this study was to determine whether tractor overturns cluster in certain parts of Kentucky and identify factors as...

A new approach for constructing tests for association between a random right censored life time variable and a covariate is proposed. The basic idea is to first arrange the observations in increasing order of the covariate and then base the test on a certain point process defined by the observation times. Tests constructed by this approach are robust against outliers in the covariate values or ...

This statistic has been the object of recent interest in the litterature. Using the saddle point method, we obtain from the generating function of the sum of positions of records in random permutations and Cauchy’s integral formula, asymptotic results in central and non-central regions. In the non-central region, we derive asymptotic expansions generalizing some results by Kortchemski. In the c...

BACKGROUND Many randomized trials involve measuring a continuous outcome - such as pain, body weight or blood pressure - at baseline and after treatment. In this paper, I compare four possibilities for how such trials can be analyzed: post-treatment; change between baseline and post-treatment; percentage change between baseline and post-treatment and analysis of covariance (ANCOVA) with baselin...

One of the main applications of balance indices is in tests of nullmodels of evolutionary processes. The knowledge of an exact formula for a statistic of a balance index, holding for any number n of leaves, is necessary in order to use this statistic in tests of this kind involving trees of any size. In this paper we obtain exact formulas for the variance under the Yule model of the Sackin, the...

Using the Kalbfleisch-Prentice marginal likelihood based on Cox's regression and life model, a computationally simple method is presented for testing general linear hypotheses of the form H o : ~ §= Q. The method, which does not require estimating §, is based on partitioning the asymptotic global chi-square statistic of Cox to produce the appropriate test statistic. Under H o ' this statistic a...

BACKGROUND: Many different test statistics have been proposed to test for spatial clustering. Some of these statistics have been widely used in various applications. In this paper, we use an existing collection of 1,220,000 simulated benchmark data, generated under 51 different clustering models, to compare the statistical power of several disease clustering tests. These tests are Besag-Newell'...

We describe a test statistic for unbinned goodness-of-fit of data in one dimension. The statistic is based on the two-dimensional Random Walk. The rejection power of this test is explored both for simple and compound hypotheses and, for the examples explored, it is found to be comparable to that for the χ test. We discuss briefly how it may be possible to extend this test to multi-dimensional d...

This study has been performed in order to analyze the coordinated degree and evolving trends of the land intensive use and land eco-security based on the statistical data from 1998 to 2007 in Chengdu city by Synergetios theory and dynamic coordinated degrees model. Results show that during the study period, the level of land intensive use and land ecological security both rose in Chengdu, the f...

BACKGROUND The spatial scan statistic is widely used by public health professionals in the detection of spatial clusters in inhomogeneous point process. The most popular version of the spatial scan statistic uses a circular-shaped scanning window. Several other variants, using other parametric or non-parametric shapes, are also available. However, none of them offer information about the uncert...