Testing for size and allometric differences in fossil hominin body mass estimation

Body size reconstructions of fossil hominins allow us to infer many things about their evolution and lifestyle, including diet, metabolic requirements, locomotion, and brain/body size relationships. The importance of these implications compels anthropologists to attempt body mass estimation from fragmentary fossil hominin specimens. Most calculations require a known “calibration” sample usually composed of modern humans or other extant apes. Caution must be taken in these analyses, as estimates are sensitive to overall size and allometric differences between the fossil hominin and the reference sample. Am J Phys Anthropol 151:215–229, 2013. © 2013 Wiley Periodicals, Inc.     

Insensitivity of Minimax Linear Estimators

If one has prior information on the unknown parameter vector β of a linear model such that ß may be assumed to lie in a concentration ellipsoid, then the resulting minimax linear estimator (MILE) is of ridge type and has smaller quadratic risk than the GLSE. This holds whenever the prior information is a true one. The relation between MILE and GLSE is investigated under incorrect specified prior regions. The MILE is said to be robust against misspecification of the prior region, if its risk stays smaller than the risk of the GLSE.     

Brief communication: discrimination between European-American and African-American children based on deciduous dental metrics and morphology

This study employs metric and morphological features of the deciduous dentition for discriminating between European-American and African-American children and providing allocation rules (regression equations). Five logistic regression equations are presented, with the percentage of correct allocation to group of between 90.1-92.6%. All five equations employ three metric traits (the mesiodistal diameters of the mandibular deciduous canines and anterior and posterior deciduous premolars) and one morphological feature (cusp number of the maxillary deciduous anterior premolar). In addition to these four variables, only two or three additional morphological features are added in carious combinations in the final equations. Correct allocation to group is 4-12% greater when combining metric and morphological features compared to using the features separately.     

Efficient resampling methods for nonsmooth estimating functions

We propose a simple and general resampling strategy to estimatevariances for parameter estimators derived from nonsmooth estimatingfunctions. This approach applies to a wide variety of semiparametricand nonparametric problems in biostatistics. It does not requiresolving estimating equations and is thus much faster than theexisting resampling procedures. Its usefulness is illustratedwith heteroscedastic quantile regression and censored data rankregression. Numerical results based on simulated and real dataare provided.     

Statistical Dose-Response Models with Hormetic Effects

Monotonically increasing or decreasing functions are often used to model the relationship between the response of an experimental unit and the dose of a given substance. Of late, there has been an increased interest in dose-response relationships that exhibit hormetic effects. These effects may be characterized by an increase in response at low doses instead of the expected decrease in response that is observed at higher doses. Herein, we study the statistical implications of hormesis in several ways. First, we present a broad class of parametric mathematical-statistical models, constructed from standard dose-response models, that allow the incorporation of hormetic effects in such a way that the presence of hormesis can be tested statistically. Second, we consider the impact of model misspecification on effective dose estimation, such as the ED50 and the limiting dose for stimulation, when the hormetic effect is present but ignored in the dose-response model by the researcher (model underspecification) and when an hormetic effect is not present but incorporated into the dose-response model (model overspecification). Our simulation study reveals that it is more damaging to the estimation of effective dose to ignore the hormetic effect through model underspecification than to include the hormetic effect in the model through model overspecification. Third, we develop a nonpara-metric regression technique useful as an exploratory procedure to indicate hormetic effects when present. Finally, both parametric and nonparametric methods are illustrated with an example.     

Estimation of random regression parameters

The problem of the best linear unbiased estimation (BLUE) of random regression parameters is considered. It is proved that increasing informations about the mean value of the parameters both extend the class of estimable linear functionals and improve on the estimation. In all investigated cases the uniqueness of BLUE is proved. In the case of known mean values the BLUE is shown to be numerically equivalent with the MMSEE almost everywhere. A numerical example shows the improvements of BLUE due to increasing informations about the mean values of the parameters.     

多元统计中Logistic回归模型参数估计的一种方法及应用

本文提出一多元统计中Logistics回归模型参数的估计方法──极大似然估计法,使得很容易在计算机上应用,并建立了大兴安岭地区秋季人为火发生预报模型。     

Age estimation from dental eruption in infant and juvenile baboons (Papio sp.)

Two regression methods are proposed for estimating age in nonhuman primates from deciduous dental eruption data. The first method consists of step-wise multiple regression using dental eruption state (present/absent) of each tooth as independent variables. The second method uses the total number of teeth erupted as an independent variable in an exponential model. We applied both methods to a sample of 175 well nourished infant and juvenile baboons (Papio sp.), housed in an outdoor breeding corral, and ranging in age from birth to 763 days. From this sample, 129 animals were used to compute the regression formulae, and 46 animals were used for cross validation. Both models show good overall fits and high predictive accuracy with the independent cross validation sample.     

苹果发酵液中残余还原糖的测定方法比较

对传统的费林定糖法、高锰酸钾滴定法和3,5－二硝基水杨酸比色定糖法测定苹果原汁及生产酒精的苹果发酵液中的还原糖进行了比较研究。测定结果显示,这三种方法的相对误差,标准偏差均十分接近。通过对此三种方法和回归相关性分析显示：比色法－高锰酸钾法的回归方程为y=1.0157x 0.0262,相关系数R^2=0.9996;比色法－费林法的回归方程为y=0.973x 0.2843,相关系数R^2=0.9984;高锰酸钾法－费林法的回归方程为y=0.9914x 0.3810,R^2=0.9973。