医学论文中logistic回归分析的误用及案例分析     

韩宏志  官鑫  李欣欣  姜瑾秋  王丽 《编辑学报》2018,30(6):586-588

logistic回归分析在医学研究领域应用较为广泛,但因其涉及的因素较多,统计方法较为复杂,部分研究者未咨询流行病学和卫生统计学专业人员而盲目套用统计学方法,造成其在应用logistic回归分析处理数据时出现诸如自变量选取和纳入、统计模型选择、结果表述和报告时误用错用情况的发生。本文选取公开发表的医学论文,举例分析文章中logistic回归误用错用的情况,指出其正确应用方法,为医学期刊编辑处理类似稿件提供参考。  相似文献   

Jacobi与Gauss—Seidel迭代法求解线性方程组收敛性比较与研究   总被引：1，自引：0，他引：1  

王育琳贺迅宇  张尚先 《株洲师范高等专科学校学报》2004,9(5):30-32

Jacobi迭代法和Gauss-Seidel迭代法是计算机求解线性方程组常用的两种迭代法,但是这两种方法对方程的收敛性要求很严,大部分方程组均不能用以求解.给出一些基本技巧:对于简单的2阶方程组,若Jacobi法与Gauss-Seidel法均发散,可交换其两行求得其解;对一般性方程,给出一个应用性较强的定理,将方程Ax=b ATAx=ATb,可以用Gauss-Seidel求得任何｜A｜≠0方程组的解.  相似文献   

Coordinating multiple representations of polynomials: What do patterns in students' solution strategies reveal?     

《Learning and Instruction》2017

We investigate the strategies used by 64 advanced secondary mathematics students to identify whether a given pair of polynomial representations (graphs, tables, or equations) corresponded to the same function on an assessment of coordinating representations. Participants also completed assessments of domain-related knowledge and background skills. Cluster analysis of strategies by representation pair revealed patterns in the participants' strategy use. Two clusters were identifiable on tasks that required matching equations to graphs and graphs to tables. We identified overlap between these two clusters, suggesting that while the representation pair influenced strategy choice, there was also a general distinction between students who used more and less sophisticated strategies. However, students who used more sophisticated coordination strategies were similar to the others on measures of domain-specific knowledge or background skills. We consider implications for future investigations testing interventions to promote coordinating representations.  相似文献   

Optimal sampling frequency in recording of resistance training exercises     

Paolo Bardella  Irene Carrasquilla García  Marco Pozzo  Julio Tous-Fajardo  Eduardo Saez de Villareal 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):102-114

The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f_99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.  相似文献   

英汉多个疑问词的句法分布     

唐燕玲  唐科 《湖南第一师范学报》2015,(2)

一个句子的焦点是句子语义的重心所在。疑问词是疑问句的语义重心，因而疑问句的焦点就是疑问词。本文以焦点和突显观为理论依据，考察了英汉多个疑问词在特指问句中的句法位置，揭示出在特指问句中英语多个wh-词移位和汉语多个疑问词原位的原因。英语特指问句中多个wh-词必须有一个移至句首，这是其自身显性的焦点性和突显性的结果。  相似文献   

Key somatic variables associated with,and differences between the 4 swimming strokes     

Alan M. Nevill  Yassine Negra  Tony D. Myers  Senda Sammoud  Helmi Chaabene 《Journal of sports sciences》2020,38(7):787-794

ABSTRACT

This study identified key somatic and demographic characteristics that benefit all swimmers and, at the same time, identified further characteristics that benefit only specific swimming strokes. Three hundred sixty-three competitive-level swimmers (male [n = 202]; female [n = 161]) participated in the study. We adopted a multiplicative, allometric regression model to identify the key characteristics associated with 100 m swimming speeds (controlling for age). The model was refined using backward elimination. Characteristics that benefited some but not all strokes were identified by introducing stroke-by-predictor variable interactions. The regression analysis revealed 7 “common” characteristics that benefited all swimmers suggesting that all swimmers benefit from having less body fat, broad shoulders and hips, a greater arm span (but shorter lower arms) and greater forearm girths with smaller relaxed arm girths. The 4 stroke-specific characteristics reveal that backstroke swimmers benefit from longer backs, a finding that can be likened to boats with longer hulls also travel faster through the water. Other stroke-by-predictor variable interactions (taken together) identified that butterfly swimmers are characterized by greater muscularity in the lower legs. These results highlight the importance of considering somatic and demographic characteristics of young swimmers for talent identification purposes (i.e., to ensure that swimmers realize their most appropriate strokes).  相似文献   

基于ActiGraph GT3X监测网球运动能量消耗的研究          下载免费PDF全文

袁川 《河北体育学院学报》2017,31(4):83-91

目的:应用ActiGraph GT3X对网球运动等非周期性运动能量消耗进行测评,建立适合网球运动能耗预测的回归方程,从而丰富ActiGraph测量体系.方法:以K4b2测量值作为校标,分别在拍柄、持拍手手腕外侧、腰部髂肌外侧、大腿中央前侧和脚踝外侧(持拍手同一侧肢体)各佩戴一个加速度计(ActiGraph GT3X),同步对网球运动中不同球速下(30 km/h、60 km/h)的原地正、反手击球,侧向移动正、反手击球,向前移动正、反手击球,侧向移动正反手交替击球和模拟自由单打的运动过程进行监测.结果:腰部、大腿和踝关节部位GT3X的EE和MET预测值存在明显低估,与K4b2测量值一致性较低;手腕和拍柄部位GT3X的EE和MET预测值存在明显高估,与K4b2测量值一致性较低;研究建立了2个网球运动能耗预测回归方程,经检验其预测值与实测值没有显著性差异.结论:运用ActiGraph GT3X对网球等隔网对抗运动项目进行监测存在显著误差,EE和MET的预测存在明显高估或低估的现象;基于ActiGraph GT3X所建立的能耗预测方程能对网球运动进行有效的运动监测.  相似文献   

An NCME Instructional Module on Data Mining Methods for Classification and Regression     

Sandip Sinharay 《Educational Measurement》2016,35(3):38-54

Data mining methods for classification and regression are becoming increasingly popular in various scientific fields. However, these methods have not been explored much in educational measurement. This module first provides a review, which should be accessible to a wide audience in education measurement, of some of these methods. The module then demonstrates using three real‐data examples that these methods may lead to an improvement over traditionally used methods such as linear and logistic regression in educational measurement.  相似文献   

Gender-preferential intergenerational patterns in primary educational attainment: An econometric approach to a case in rural Mindanao,the Philippines     

《International Journal of Educational Development》2016

This study investigates the factors determining children's educational attainment, focusing on gender-differential intergenerational patterns, by employing a case study from rural Mindanao. The result mainly shows, unlike general trends in developing countries, educational attainment is more favorable for girls; maternal education level is equally associated with daughters’ and sons’ education levels, and paternal education level is preferentially favorable to their sons. To reduce the disparity, suggestions include providing boy-specific interventions to enhance the magnitude of the father–son educational virtuous circle and comparing the magnitude of gender-equal maternal and boy-preferential paternal education influences to specify which effect is larger.  相似文献   

跨学科类比法在线性代数教学中的应用     

罗兰兰 《四川教育学院学报》2011,27(1):119-121

针对线性代数教学的抽象与沉闷的现状,结合当前大学生的时代特性与兴趣特性,文章将以一个教学实例为对象,尝试使用跨学科类比法,并以此为突破口,试图探索生活化的＂去数学化＂的新型教学。  相似文献